diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6ecca9678..12b595933 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,10 +10,12 @@ and this project adheres to [Semantic Versioning](https://semver.org).
 ### Added
 
 - Xlsx Reader Optionally Ignore Rows With No Cells. [Issue #3982](https://github.com/PHPOffice/PhpSpreadsheet/issues/3982) [PR #4035](https://github.com/PHPOffice/PhpSpreadsheet/pull/4035)
+- Option for CSV output file to have varying numbers of columns for each row. [Issue #1415](https://github.com/PHPOffice/PhpSpreadsheet/issues/1415) [PR #4076](https://github.com/PHPOffice/PhpSpreadsheet/pull/4076)
 
 ### Changed
 
 - On read, Xlsx Reader had been breaking up union ranges into separate individual ranges. It will now try to preserve range as it was read in. [PR #4042](https://github.com/PHPOffice/PhpSpreadsheet/pull/4042)
+- Xlsx/Xls spreadsheet calculation and formatting of dates will use base date of spreadsheet even when spreadsheets with different base dates are simultaneously open. [Issue #1036](https://github.com/PHPOffice/PhpSpreadsheet/issues/1036) [Issue #1635](https://github.com/PHPOffice/PhpSpreadsheet/issues/1635) [PR #4071](https://github.com/PHPOffice/PhpSpreadsheet/pull/4071) 
 
 ### Deprecated
 
@@ -32,7 +34,10 @@ and this project adheres to [Semantic Versioning](https://semver.org).
 - Mpdf and Tcpdf Borders on Merged Cells. [Issue #3557](https://github.com/PHPOffice/PhpSpreadsheet/issues/3557) [PR #4047](https://github.com/PHPOffice/PhpSpreadsheet/pull/4047)
 - Xls Conditional Format Improvements. [PR #4030](https://github.com/PHPOffice/PhpSpreadsheet/pull/4030) [PR #4033](https://github.com/PHPOffice/PhpSpreadsheet/pull/4033)
 - Conditional Range Unions and Intersections [Issue #4039](https://github.com/PHPOffice/PhpSpreadsheet/issues/4039) [PR #4042](https://github.com/PHPOffice/PhpSpreadsheet/pull/4042)
-- Csv Reader allow use of html mimetype. [Issue #4036](https://github.com/PHPOffice/PhpSpreadsheet/issues/4036) [PR #4049](https://github.com/PHPOffice/PhpSpreadsheet/pull/4040)
+- Csv Reader allow use of html mimetype. [Issue #4036](https://github.com/PHPOffice/PhpSpreadsheet/issues/4036) [PR #4040](https://github.com/PHPOffice/PhpSpreadsheet/pull/4040)
+- Problem rendering line chart with missing plot label. [PR #4074](https://github.com/PHPOffice/PhpSpreadsheet/pull/4074)
+- More RTL in Xlsx/Html Comments [Issue #4004](https://github.com/PHPOffice/PhpSpreadsheet/issues/4004) [PR #4065](https://github.com/PHPOffice/PhpSpreadsheet/pull/4065)
+- Empty String in sharedStrings. [Issue #4063](https://github.com/PHPOffice/PhpSpreadsheet/issues/4063) [PR #4064](https://github.com/PHPOffice/PhpSpreadsheet/pull/4064)
 
 ## 2024-05-11 - 2.1.0
 
diff --git a/docs/topics/Looping the Loop.md b/docs/topics/Looping the Loop.md
index 0b48d0976..046db3a13 100644
--- a/docs/topics/Looping the Loop.md	
+++ b/docs/topics/Looping the Loop.md	
@@ -308,6 +308,28 @@ But a peak memory usage of 49,152KB compared with the 57,344KB used by `toArray(
 Like `toArray()`, `rangeToArray()` is easy to use, but it has the same limitations for flexibility. It provides the same limited control over how the data from each cell is returned in the array as `toArray()`.
 The same additional arguments that can be provided for the `toArray()` method can also be provided to `rangeToArray()`.
 
+
+## Using `rangeToArrayYieldRows()`
+
+Since v2.1.0 the worksheet method `rangeToArrayYieldRows()` is available.
+It allows you to iterate over all sheet's rows with little memory consumption,
+while obtaining each row as an array:
+
+```php
+$rowGenerator = $sheet->rangeToArrayYieldRows(
+    'A1:' . $sheet->getHighestDataColumn() . $sheet->getHighestDataRow(),
+    null,
+    false,
+    false
+);
+foreach ($rowGenerator as $row) {
+    echo $row[0] . ' | ' . $row[1] . "\n";
+}
+```
+
+See `samples/Reader2/23_iterateRowsYield.php`.
+
+
 ## Using Iterators
 
 You don't need to build an array from the worksheet to loop through the rows and columns and do whatever processing you need; you can loop through the rows and columns in the Worksheet directly and more efficiently using PhpSpreadsheet's built-in iterators.
diff --git a/docs/topics/reading-and-writing-to-file.md b/docs/topics/reading-and-writing-to-file.md
index 389917952..aa6298df9 100644
--- a/docs/topics/reading-and-writing-to-file.md
+++ b/docs/topics/reading-and-writing-to-file.md
@@ -679,6 +679,18 @@ $writer->setOutputEncoding('SJIS-WIN');
 $writer->save("05featuredemo.csv");
 ```
 
+#### Writing CSV files with varying numbers of columns
+
+A CSV file can have a different number of columns in each row. This
+differs from the default behavior when saving as a .csv in Excel, but
+can be enabled in PhpSpreadsheet by using the following code:
+
+``` php
+$writer = new \PhpOffice\PhpSpreadsheet\Writer\Csv($spreadsheet);
+$writer->setVariableColumns(true);
+$writer->save("05featuredemo.csv");
+```
+
 #### Decimal and thousands separators
 
 If the worksheet you are exporting contains numbers with decimal or
diff --git a/samples/Reader2/23_iterateRowsYield.php b/samples/Reader2/23_iterateRowsYield.php
new file mode 100644
index 000000000..f1a7ef88f
--- /dev/null
+++ b/samples/Reader2/23_iterateRowsYield.php
@@ -0,0 +1,25 @@
+<?php
+
+/**
+ * Use rangeToArrayYieldRows() to efficiently iterate over all rows.
+ */
+
+require __DIR__ . '/../Header.php';
+
+$inputFileName = __DIR__ . '/../Reader/sampleData/example1.xls';
+
+$spreadsheet = PhpOffice\PhpSpreadsheet\IOFactory::load(
+    $inputFileName,
+    PhpOffice\PhpSpreadsheet\Reader\IReader::READ_DATA_ONLY
+);
+$sheet = $spreadsheet->getSheet(0);
+
+$rowGenerator = $sheet->rangeToArrayYieldRows(
+    $spreadsheet->getActiveSheet()->calculateWorksheetDataDimension(),
+    null,
+    false,
+    false
+);
+foreach ($rowGenerator as $row) {
+    echo '| ' . $row[0] . ' | ' . $row[1] . "|\n";
+}
diff --git a/src/PhpSpreadsheet/Calculation/Calculation.php b/src/PhpSpreadsheet/Calculation/Calculation.php
index 76b1a54f6..257d1d06c 100644
--- a/src/PhpSpreadsheet/Calculation/Calculation.php
+++ b/src/PhpSpreadsheet/Calculation/Calculation.php
@@ -122,7 +122,7 @@ class Calculation
      */
     private Logger $debugLog;
 
-    private bool $suppressFormulaErrorsNew = false;
+    private bool $suppressFormulaErrors = false;
 
     /**
      * Error message for any error that was raised/thrown by the calculation engine.
@@ -5382,7 +5382,7 @@ class Calculation
     {
         $this->formulaError = $errorMessage;
         $this->cyclicReferenceStack->clear();
-        $suppress = $this->suppressFormulaErrors ?? $this->suppressFormulaErrorsNew;
+        $suppress = $this->suppressFormulaErrors;
         if (!$suppress) {
             throw new Exception($errorMessage, $code, $exception);
         }
@@ -5666,12 +5666,12 @@ class Calculation
 
     public function setSuppressFormulaErrors(bool $suppressFormulaErrors): void
     {
-        $this->suppressFormulaErrorsNew = $suppressFormulaErrors;
+        $this->suppressFormulaErrors = $suppressFormulaErrors;
     }
 
     public function getSuppressFormulaErrors(): bool
     {
-        return $this->suppressFormulaErrorsNew;
+        return $this->suppressFormulaErrors;
     }
 
     public static function boolToString(mixed $operand1): mixed
diff --git a/src/PhpSpreadsheet/Cell/AdvancedValueBinder.php b/src/PhpSpreadsheet/Cell/AdvancedValueBinder.php
index 08bb7ae67..416864529 100644
--- a/src/PhpSpreadsheet/Cell/AdvancedValueBinder.php
+++ b/src/PhpSpreadsheet/Cell/AdvancedValueBinder.php
@@ -4,7 +4,6 @@ namespace PhpOffice\PhpSpreadsheet\Cell;
 
 use PhpOffice\PhpSpreadsheet\Calculation\Calculation;
 use PhpOffice\PhpSpreadsheet\Calculation\Engine\FormattedNumber;
-use PhpOffice\PhpSpreadsheet\RichText\RichText;
 use PhpOffice\PhpSpreadsheet\Shared\Date;
 use PhpOffice\PhpSpreadsheet\Shared\StringHelper;
 use PhpOffice\PhpSpreadsheet\Style\NumberFormat;
@@ -30,7 +29,7 @@ class AdvancedValueBinder extends DefaultValueBinder implements IValueBinder
         $dataType = parent::dataTypeForValue($value);
 
         // Style logic - strings
-        if ($dataType === DataType::TYPE_STRING && !$value instanceof RichText) {
+        if ($dataType === DataType::TYPE_STRING && is_string($value)) {
             //    Test for booleans using locale-setting
             if (StringHelper::strToUpper($value) === Calculation::getTRUE()) {
                 $cell->setValueExplicit(true, DataType::TYPE_BOOL);
@@ -54,17 +53,17 @@ class AdvancedValueBinder extends DefaultValueBinder implements IValueBinder
             $thousandsSeparator = preg_quote(StringHelper::getThousandsSeparator(), '/');
 
             // Check for percentage
-            if (preg_match('/^\-?\d*' . $decimalSeparator . '?\d*\s?\%$/', preg_replace('/(\d)' . $thousandsSeparator . '(\d)/u', '$1$2', $value))) {
-                return $this->setPercentage(preg_replace('/(\d)' . $thousandsSeparator . '(\d)/u', '$1$2', $value), $cell);
+            if (preg_match('/^\-?\d*' . $decimalSeparator . '?\d*\s?\%$/', (string) preg_replace('/(\d)' . $thousandsSeparator . '(\d)/u', '$1$2', $value))) {
+                return $this->setPercentage((string) preg_replace('/(\d)' . $thousandsSeparator . '(\d)/u', '$1$2', $value), $cell);
             }
 
             // Check for currency
-            if (preg_match(FormattedNumber::currencyMatcherRegexp(), preg_replace('/(\d)' . $thousandsSeparator . '(\d)/u', '$1$2', $value), $matches, PREG_UNMATCHED_AS_NULL)) {
+            if (preg_match(FormattedNumber::currencyMatcherRegexp(), (string) preg_replace('/(\d)' . $thousandsSeparator . '(\d)/u', '$1$2', $value), $matches, PREG_UNMATCHED_AS_NULL)) {
                 // Convert value to number
                 $sign = ($matches['PrefixedSign'] ?? $matches['PrefixedSign2'] ?? $matches['PostfixedSign']) ?? null;
                 $currencyCode = $matches['PrefixedCurrency'] ?? $matches['PostfixedCurrency'];
                 /** @var string */
-                $temp = str_replace([$decimalSeparatorNoPreg, $currencyCode, ' ', '-'], ['.', '', '', ''], preg_replace('/(\d)' . $thousandsSeparator . '(\d)/u', '$1$2', $value));
+                $temp = str_replace([$decimalSeparatorNoPreg, $currencyCode, ' ', '-'], ['.', '', '', ''], (string) preg_replace('/(\d)' . $thousandsSeparator . '(\d)/u', '$1$2', $value));
                 $value = (float) ($sign . trim($temp));
 
                 return $this->setCurrency($value, $cell, $currencyCode ?? '');
diff --git a/src/PhpSpreadsheet/Cell/Cell.php b/src/PhpSpreadsheet/Cell/Cell.php
index 880cc609f..e205b73ee 100644
--- a/src/PhpSpreadsheet/Cell/Cell.php
+++ b/src/PhpSpreadsheet/Cell/Cell.php
@@ -189,14 +189,21 @@ class Cell implements Stringable
      */
     public function getFormattedValue(): string
     {
-        return (string) NumberFormat::toFormattedString(
+        $currentCalendar = SharedDate::getExcelCalendar();
+        SharedDate::setExcelCalendar($this->getWorksheet()->getParent()?->getExcelCalendar());
+        $formattedValue = (string) NumberFormat::toFormattedString(
             $this->getCalculatedValue(),
             (string) $this->getStyle()->getNumberFormat()->getFormatCode(true)
         );
+        SharedDate::setExcelCalendar($currentCalendar);
+
+        return $formattedValue;
     }
 
     protected static function updateIfCellIsTableHeader(?Worksheet $workSheet, self $cell, mixed $oldValue, mixed $newValue): void
     {
+        $oldValue = (is_scalar($oldValue) || $oldValue instanceof Stringable) ? ((string) $oldValue) : null;
+        $newValue = (is_scalar($newValue) || $newValue instanceof Stringable) ? ((string) $newValue) : null;
         if (StringHelper::strToLower($oldValue ?? '') === StringHelper::strToLower($newValue ?? '') || $workSheet === null) {
             return;
         }
@@ -264,7 +271,10 @@ class Cell implements Stringable
                 // Synonym for string
             case DataType::TYPE_INLINE:
                 // Rich text
-                $this->value = DataType::checkString($value);
+                if ($value !== null && !is_scalar($value) && !($value instanceof Stringable)) {
+                    throw new SpreadsheetException('Invalid unstringable value for datatype Inline/String/String2');
+                }
+                $this->value = DataType::checkString(($value instanceof RichText) ? $value : ((string) $value));
 
                 break;
             case DataType::TYPE_NUMERIC:
@@ -385,6 +395,8 @@ class Cell implements Stringable
 
         if ($this->dataType === DataType::TYPE_FORMULA) {
             try {
+                $currentCalendar = SharedDate::getExcelCalendar();
+                SharedDate::setExcelCalendar($this->getWorksheet()->getParent()?->getExcelCalendar());
                 $index = $this->getWorksheet()->getParentOrThrow()->getActiveSheetIndex();
                 $selected = $this->getWorksheet()->getSelectedCells();
                 $thisworksheet = $this->getWorksheet();
@@ -509,6 +521,7 @@ class Cell implements Stringable
                     $this->dataType = $originalDataType;
                 }
             } catch (SpreadsheetException $ex) {
+                SharedDate::setExcelCalendar($currentCalendar);
                 if (($ex->getMessage() === 'Unable to access External Workbook') && ($this->calculatedValue !== null)) {
                     return $this->calculatedValue; // Fallback for calculations referencing external files.
                 } elseif (preg_match('/[Uu]ndefined (name|offset: 2|array key 2)/', $ex->getMessage()) === 1) {
@@ -521,6 +534,7 @@ class Cell implements Stringable
                     $ex
                 );
             }
+            SharedDate::setExcelCalendar($currentCalendar);
 
             if ($result === '#Not Yet Implemented') {
                 return $this->calculatedValue; // Fallback if calculation engine does not support the formula.
@@ -924,7 +938,9 @@ class Cell implements Stringable
      */
     public function __toString(): string
     {
-        return (string) $this->getValue();
+        $retVal = $this->value;
+
+        return ($retVal === null || is_scalar($retVal) || $retVal instanceof Stringable) ? ((string) $retVal) : '';
     }
 
     public function getIgnoredErrors(): IgnoredErrors
diff --git a/src/PhpSpreadsheet/Cell/DataType.php b/src/PhpSpreadsheet/Cell/DataType.php
index 8ae11df06..a213725c0 100644
--- a/src/PhpSpreadsheet/Cell/DataType.php
+++ b/src/PhpSpreadsheet/Cell/DataType.php
@@ -4,6 +4,7 @@ namespace PhpOffice\PhpSpreadsheet\Cell;
 
 use PhpOffice\PhpSpreadsheet\RichText\RichText;
 use PhpOffice\PhpSpreadsheet\Shared\StringHelper;
+use Stringable;
 
 class DataType
 {
@@ -78,7 +79,7 @@ class DataType
      */
     public static function checkErrorCode(mixed $value): string
     {
-        $value = (string) $value;
+        $value = (is_scalar($value) || $value instanceof Stringable) ? ((string) $value) : '#NULL!';
 
         if (!isset(self::$errorCodes[$value])) {
             $value = '#NULL!';
diff --git a/src/PhpSpreadsheet/Cell/DataValidator.php b/src/PhpSpreadsheet/Cell/DataValidator.php
index a3524dfb1..63ef8999f 100644
--- a/src/PhpSpreadsheet/Cell/DataValidator.php
+++ b/src/PhpSpreadsheet/Cell/DataValidator.php
@@ -46,7 +46,7 @@ class DataValidator
                 $returnValue = $this->numericOperator($dataValidation, (float) $cellValue);
             }
         } elseif ($type === DataValidation::TYPE_TEXTLENGTH) {
-            $returnValue = $this->numericOperator($dataValidation, mb_strlen((string) $cellValue));
+            $returnValue = $this->numericOperator($dataValidation, mb_strlen($cell->getValueString()));
         }
 
         return $returnValue;
@@ -86,14 +86,14 @@ class DataValidator
      */
     private function isValueInList(Cell $cell): bool
     {
-        $cellValue = $cell->getValue();
+        $cellValueString = $cell->getValueString();
         $dataValidation = $cell->getDataValidation();
 
         $formula1 = $dataValidation->getFormula1();
         if (!empty($formula1)) {
             // inline values list
             if ($formula1[0] === '"') {
-                return in_array(strtolower($cellValue), explode(',', strtolower(trim($formula1, '"'))), true);
+                return in_array(strtolower($cellValueString), explode(',', strtolower(trim($formula1, '"'))), true);
             } elseif (strpos($formula1, ':') > 0) {
                 // values list cells
                 $matchFormula = '=MATCH(' . $cell->getCoordinate() . ', ' . $formula1 . ', 0)';
diff --git a/src/PhpSpreadsheet/Cell/DefaultValueBinder.php b/src/PhpSpreadsheet/Cell/DefaultValueBinder.php
index 2710ead43..6f75a90a8 100644
--- a/src/PhpSpreadsheet/Cell/DefaultValueBinder.php
+++ b/src/PhpSpreadsheet/Cell/DefaultValueBinder.php
@@ -46,19 +46,33 @@ class DefaultValueBinder implements IValueBinder
         // Match the value against a few data types
         if ($value === null) {
             return DataType::TYPE_NULL;
-        } elseif (is_float($value) || is_int($value)) {
+        }
+        if (is_float($value) || is_int($value)) {
             return DataType::TYPE_NUMERIC;
-        } elseif (is_bool($value)) {
+        }
+        if (is_bool($value)) {
             return DataType::TYPE_BOOL;
-        } elseif ($value === '') {
+        }
+        if ($value === '') {
             return DataType::TYPE_STRING;
-        } elseif ($value instanceof RichText) {
+        }
+        if ($value instanceof RichText) {
             return DataType::TYPE_INLINE;
-        } elseif (is_string($value) && strlen($value) > 1 && $value[0] === '=') {
+        }
+        if ($value instanceof Stringable) {
+            $value = (string) $value;
+        }
+        if (!is_string($value)) {
+            $gettype = is_object($value) ? get_class($value) : gettype($value);
+
+            throw new SpreadsheetException("unusable type $gettype");
+        }
+        if (strlen($value) > 1 && $value[0] === '=') {
             return DataType::TYPE_FORMULA;
-        } elseif (preg_match('/^[\+\-]?(\d+\\.?\d*|\d*\\.?\d+)([Ee][\-\+]?[0-2]?\d{1,3})?$/', $value)) {
+        }
+        if (preg_match('/^[\+\-]?(\d+\\.?\d*|\d*\\.?\d+)([Ee][\-\+]?[0-2]?\d{1,3})?$/', $value)) {
             $tValue = ltrim($value, '+-');
-            if (is_string($value) && strlen($tValue) > 1 && $tValue[0] === '0' && $tValue[1] !== '.') {
+            if (strlen($tValue) > 1 && $tValue[0] === '0' && $tValue[1] !== '.') {
                 return DataType::TYPE_STRING;
             } elseif ((!str_contains($value, '.')) && ($value > PHP_INT_MAX)) {
                 return DataType::TYPE_STRING;
@@ -67,11 +81,10 @@ class DefaultValueBinder implements IValueBinder
             }
 
             return DataType::TYPE_NUMERIC;
-        } elseif (is_string($value)) {
-            $errorCodes = DataType::getErrorCodes();
-            if (isset($errorCodes[$value])) {
-                return DataType::TYPE_ERROR;
-            }
+        }
+        $errorCodes = DataType::getErrorCodes();
+        if (isset($errorCodes[$value])) {
+            return DataType::TYPE_ERROR;
         }
 
         return DataType::TYPE_STRING;
diff --git a/src/PhpSpreadsheet/Chart/Axis.php b/src/PhpSpreadsheet/Chart/Axis.php
index 9d8000e3d..dc1fca4fd 100644
--- a/src/PhpSpreadsheet/Chart/Axis.php
+++ b/src/PhpSpreadsheet/Chart/Axis.php
@@ -37,7 +37,7 @@ class Axis extends Properties
     /**
      * Axis Number.
      *
-     * @var mixed[]
+     * @var array{format: string, source_linked: int, numeric: ?bool}
      */
     private array $axisNumber = [
         'format' => self::FORMAT_CODE_GENERAL,
diff --git a/src/PhpSpreadsheet/Chart/DataSeriesValues.php b/src/PhpSpreadsheet/Chart/DataSeriesValues.php
index 3f105eeca..70f90bf78 100644
--- a/src/PhpSpreadsheet/Chart/DataSeriesValues.php
+++ b/src/PhpSpreadsheet/Chart/DataSeriesValues.php
@@ -451,12 +451,14 @@ class DataSeriesValues extends Properties
                 if (($dimensions[0] == 1) || ($dimensions[1] == 1)) {
                     $this->dataValues = Functions::flattenArray($newDataValues);
                 } else {
-                    $newArray = array_values(array_shift($newDataValues));
+                    /** @var array<int, array> */
+                    $newDataValuesx = $newDataValues;
+                    $newArray = array_values(array_shift($newDataValuesx) ?? []);
                     foreach ($newArray as $i => $newDataSet) {
                         $newArray[$i] = [$newDataSet];
                     }
 
-                    foreach ($newDataValues as $newDataSet) {
+                    foreach ($newDataValuesx as $newDataSet) {
                         $i = 0;
                         foreach ($newDataSet as $newDataVal) {
                             array_unshift($newArray[$i++], $newDataVal);
diff --git a/src/PhpSpreadsheet/Chart/Properties.php b/src/PhpSpreadsheet/Chart/Properties.php
index 9b294145a..655e79c85 100644
--- a/src/PhpSpreadsheet/Chart/Properties.php
+++ b/src/PhpSpreadsheet/Chart/Properties.php
@@ -647,8 +647,16 @@ abstract class Properties
                 'alpha' => $this->shadowColor->getAlpha(),
             ];
         }
+        $retVal = $this->getArrayElementsValue($this->shadowProperties, $elements);
+        if (is_scalar($retVal)) {
+            $retVal = (string) $retVal;
+        } elseif ($retVal !== null && !is_array($retVal)) {
+            // @codeCoverageIgnoreStart
+            throw new Exception('Unexpected value for shadowProperty');
+            // @codeCoverageIgnoreEnd
+        }
 
-        return $this->getArrayElementsValue($this->shadowProperties, $elements);
+        return $retVal;
     }
 
     public function getShadowArray(): array
@@ -825,7 +833,16 @@ abstract class Properties
      */
     public function getLineStyleProperty(array|string $elements): ?string
     {
-        return $this->getArrayElementsValue($this->lineStyleProperties, $elements);
+        $retVal = $this->getArrayElementsValue($this->lineStyleProperties, $elements);
+        if (is_scalar($retVal)) {
+            $retVal = (string) $retVal;
+        } elseif ($retVal !== null) {
+            // @codeCoverageIgnoreStart
+            throw new Exception('Unexpected value for lineStyleProperty');
+            // @codeCoverageIgnoreEnd
+        }
+
+        return $retVal;
     }
 
     protected const ARROW_SIZES = [
diff --git a/src/PhpSpreadsheet/Chart/Renderer/JpGraphRendererBase.php b/src/PhpSpreadsheet/Chart/Renderer/JpGraphRendererBase.php
index 7c21a131a..151d5b58c 100644
--- a/src/PhpSpreadsheet/Chart/Renderer/JpGraphRendererBase.php
+++ b/src/PhpSpreadsheet/Chart/Renderer/JpGraphRendererBase.php
@@ -281,6 +281,16 @@ abstract class JpGraphRendererBase implements IRenderer
         $this->renderTitle();
     }
 
+    private function getDataLabel(int $groupId, int $index): mixed
+    {
+        $plotLabel = $this->chart->getPlotArea()->getPlotGroupByIndex($groupId)->getPlotLabelByIndex($index);
+        if (!$plotLabel) {
+            return '';
+        }
+
+        return $plotLabel->getDataValue();
+    }
+
     private function renderPlotLine(int $groupID, bool $filled = false, bool $combination = false): void
     {
         $grouping = $this->chart->getPlotArea()->getPlotGroupByIndex($groupID)->getPlotGrouping();
@@ -334,8 +344,8 @@ abstract class JpGraphRendererBase implements IRenderer
                 //    Set the appropriate plot marker
                 $this->formatPointMarker($seriesPlot, $marker);
             }
-            $dataLabel = $this->chart->getPlotArea()->getPlotGroupByIndex($groupID)->getPlotLabelByIndex($index)->getDataValue();
-            $seriesPlot->SetLegend($dataLabel);
+
+            $seriesPlot->SetLegend($this->getDataLabel($groupID, $index));
 
             $seriesPlots[] = $seriesPlot;
         }
@@ -408,12 +418,8 @@ abstract class JpGraphRendererBase implements IRenderer
             if ($dimensions == '3d') {
                 $seriesPlot->SetShadow();
             }
-            if (!$this->chart->getPlotArea()->getPlotGroupByIndex($groupID)->getPlotLabelByIndex($j)) {
-                $dataLabel = '';
-            } else {
-                $dataLabel = $this->chart->getPlotArea()->getPlotGroupByIndex($groupID)->getPlotLabelByIndex($j)->getDataValue();
-            }
-            $seriesPlot->SetLegend($dataLabel);
+
+            $seriesPlot->SetLegend($this->getDataLabel($groupID, $j));
 
             $seriesPlots[] = $seriesPlot;
         }
@@ -492,8 +498,7 @@ abstract class JpGraphRendererBase implements IRenderer
                 $marker = $this->chart->getPlotArea()->getPlotGroupByIndex($groupID)->getPlotValuesByIndex($i)->getPointMarker();
                 $this->formatPointMarker($seriesPlot, $marker);
             }
-            $dataLabel = $this->chart->getPlotArea()->getPlotGroupByIndex($groupID)->getPlotLabelByIndex($i)->getDataValue();
-            $seriesPlot->SetLegend($dataLabel);
+            $seriesPlot->SetLegend($this->getDataLabel($groupID, $i));
 
             $this->graph->Add($seriesPlot);
         }
@@ -524,13 +529,12 @@ abstract class JpGraphRendererBase implements IRenderer
 
             $seriesPlot = new RadarPlot(array_reverse($dataValuesX));
 
-            $dataLabel = $this->chart->getPlotArea()->getPlotGroupByIndex($groupID)->getPlotLabelByIndex($i)->getDataValue();
             $seriesPlot->SetColor(self::$colourSet[self::$plotColour++]);
             if ($radarStyle == 'filled') {
                 $seriesPlot->SetFillColor(self::$colourSet[self::$plotColour]);
             }
             $this->formatPointMarker($seriesPlot, $marker);
-            $seriesPlot->SetLegend($dataLabel);
+            $seriesPlot->SetLegend($this->getDataLabel($groupID, $i));
 
             $this->graph->Add($seriesPlot);
         }
diff --git a/src/PhpSpreadsheet/Comment.php b/src/PhpSpreadsheet/Comment.php
index 1c07b5154..2e18270c1 100644
--- a/src/PhpSpreadsheet/Comment.php
+++ b/src/PhpSpreadsheet/Comment.php
@@ -63,6 +63,14 @@ class Comment implements IComparable, Stringable
      */
     private Drawing $backgroundImage;
 
+    public const TEXTBOX_DIRECTION_RTL = 'rtl';
+    public const TEXTBOX_DIRECTION_LTR = 'ltr';
+    // MS uses 'auto' in xml but 'context' in UI
+    public const TEXTBOX_DIRECTION_AUTO = 'auto';
+    public const TEXTBOX_DIRECTION_CONTEXT = 'auto';
+
+    private string $textboxDirection = '';
+
     /**
      * Create a new Comment.
      */
@@ -232,9 +240,6 @@ class Comment implements IComparable, Stringable
         return $this->fillColor;
     }
 
-    /**
-     * Set Alignment.
-     */
     public function setAlignment(string $alignment): self
     {
         $this->alignment = $alignment;
@@ -242,14 +247,23 @@ class Comment implements IComparable, Stringable
         return $this;
     }
 
-    /**
-     * Get Alignment.
-     */
     public function getAlignment(): string
     {
         return $this->alignment;
     }
 
+    public function setTextboxDirection(string $textboxDirection): self
+    {
+        $this->textboxDirection = $textboxDirection;
+
+        return $this;
+    }
+
+    public function getTextboxDirection(): string
+    {
+        return $this->textboxDirection;
+    }
+
     /**
      * Get hash code.
      */
@@ -265,6 +279,7 @@ class Comment implements IComparable, Stringable
             . ($this->visible ? 1 : 0)
             . $this->fillColor->getHashCode()
             . $this->alignment
+            . $this->textboxDirection
             . ($this->hasBackgroundImage() ? $this->backgroundImage->getHashCode() : '')
             . __CLASS__
         );
diff --git a/src/PhpSpreadsheet/Reader/Html.php b/src/PhpSpreadsheet/Reader/Html.php
index d365fbf23..cc4a4859a 100644
--- a/src/PhpSpreadsheet/Reader/Html.php
+++ b/src/PhpSpreadsheet/Reader/Html.php
@@ -9,6 +9,7 @@ use DOMNode;
 use DOMText;
 use PhpOffice\PhpSpreadsheet\Cell\Coordinate;
 use PhpOffice\PhpSpreadsheet\Cell\DataType;
+use PhpOffice\PhpSpreadsheet\Comment;
 use PhpOffice\PhpSpreadsheet\Document\Properties;
 use PhpOffice\PhpSpreadsheet\Exception as SpreadsheetException;
 use PhpOffice\PhpSpreadsheet\Helper\Dimension as CssDimension;
@@ -332,6 +333,15 @@ class Html extends BaseReader
                 $sheet->getComment($column . $row)
                     ->getText()
                     ->createTextRun($child->textContent);
+                if (isset($attributeArray['dir']) && $attributeArray['dir'] === 'rtl') {
+                    $sheet->getComment($column . $row)->setTextboxDirection(Comment::TEXTBOX_DIRECTION_RTL);
+                }
+                if (isset($attributeArray['style'])) {
+                    $alignStyle = $attributeArray['style'];
+                    if (preg_match('/\\btext-align:\\s*(left|right|center|justify)\\b/', $alignStyle, $matches) === 1) {
+                        $sheet->getComment($column . $row)->setAlignment($matches[1]);
+                    }
+                }
             } else {
                 $this->processDomElement($child, $sheet, $row, $column, $cellContent);
             }
diff --git a/src/PhpSpreadsheet/Reader/Xls.php b/src/PhpSpreadsheet/Reader/Xls.php
index 58a22835d..be9ccb268 100644
--- a/src/PhpSpreadsheet/Reader/Xls.php
+++ b/src/PhpSpreadsheet/Reader/Xls.php
@@ -1927,8 +1927,10 @@ class Xls extends BaseReader
 
         // offset: 0; size: 2; 0 = base 1900, 1 = base 1904
         Date::setExcelCalendar(Date::CALENDAR_WINDOWS_1900);
+        $this->spreadsheet->setExcelCalendar(Date::CALENDAR_WINDOWS_1900);
         if (ord($recordData[0]) == 1) {
             Date::setExcelCalendar(Date::CALENDAR_MAC_1904);
+            $this->spreadsheet->setExcelCalendar(Date::CALENDAR_MAC_1904);
         }
     }
 
diff --git a/src/PhpSpreadsheet/Reader/Xlsx.php b/src/PhpSpreadsheet/Reader/Xlsx.php
index c45700cc4..bcf245973 100644
--- a/src/PhpSpreadsheet/Reader/Xlsx.php
+++ b/src/PhpSpreadsheet/Reader/Xlsx.php
@@ -6,6 +6,7 @@ use PhpOffice\PhpSpreadsheet\Calculation\Information\ExcelError;
 use PhpOffice\PhpSpreadsheet\Cell\Coordinate;
 use PhpOffice\PhpSpreadsheet\Cell\DataType;
 use PhpOffice\PhpSpreadsheet\Cell\Hyperlink;
+use PhpOffice\PhpSpreadsheet\Comment;
 use PhpOffice\PhpSpreadsheet\DefinedName;
 use PhpOffice\PhpSpreadsheet\Reader\Security\XmlScanner;
 use PhpOffice\PhpSpreadsheet\Reader\Xlsx\AutoFilter;
@@ -703,6 +704,8 @@ class Xlsx extends BaseReader
                                     $sharedStrings[] = StringHelper::controlCharacterOOXML2PHP((string) $val->t);
                                 } elseif (isset($val->r)) {
                                     $sharedStrings[] = $this->parseRichText($val);
+                                } else {
+                                    $sharedStrings[] = '';
                                 }
                             }
                         }
@@ -712,12 +715,14 @@ class Xlsx extends BaseReader
                     $xmlWorkbookNS = $this->loadZip($relTarget, $mainNS);
 
                     // Set base date
+                    $excel->setExcelCalendar(Date::CALENDAR_WINDOWS_1900);
                     if ($xmlWorkbookNS->workbookPr) {
                         Date::setExcelCalendar(Date::CALENDAR_WINDOWS_1900);
                         $attrs1904 = self::getAttributes($xmlWorkbookNS->workbookPr);
                         if (isset($attrs1904['date1904'])) {
                             if (self::boolean((string) $attrs1904['date1904'])) {
                                 Date::setExcelCalendar(Date::CALENDAR_MAC_1904);
+                                $excel->setExcelCalendar(Date::CALENDAR_MAC_1904);
                             }
                         }
                     }
@@ -1153,6 +1158,14 @@ class Xlsx extends BaseReader
                                             $fillImageTitle = '';
 
                                             $clientData = $shape->xpath('.//x:ClientData');
+                                            $textboxDirection = '';
+                                            $textboxPath = $shape->xpath('.//v:textbox');
+                                            $textbox = (string) ($textboxPath[0]['style'] ?? '');
+                                            if (preg_match('/rtl/i', $textbox) === 1) {
+                                                $textboxDirection = Comment::TEXTBOX_DIRECTION_RTL;
+                                            } elseif (preg_match('/ltr/i', $textbox) === 1) {
+                                                $textboxDirection = Comment::TEXTBOX_DIRECTION_LTR;
+                                            }
                                             if (is_array($clientData) && !empty($clientData)) {
                                                 $clientData = $clientData[0];
 
@@ -1168,7 +1181,7 @@ class Xlsx extends BaseReader
                                                     }
                                                     $temp = $clientData->xpath('.//x:TextHAlign');
                                                     if (!empty($temp)) {
-                                                        $textHAlign = $temp[0];
+                                                        $textHAlign = strtolower($temp[0]);
                                                     }
                                                 }
                                             }
@@ -1177,6 +1190,9 @@ class Xlsx extends BaseReader
                                             if (is_numeric($rowx) && is_numeric($colx) && $textHAlign !== null) {
                                                 $docSheet->getComment([1 + (int) $colx, 1 + (int) $rowx], false)->setAlignment((string) $textHAlign);
                                             }
+                                            if (is_numeric($rowx) && is_numeric($colx) && $textboxDirection !== '') {
+                                                $docSheet->getComment([1 + (int) $colx, 1 + (int) $rowx], false)->setTextboxDirection($textboxDirection);
+                                            }
 
                                             $fillImageRelNode = $shape->xpath('.//v:fill/@o:relid');
                                             if (is_array($fillImageRelNode) && !empty($fillImageRelNode)) {
diff --git a/src/PhpSpreadsheet/ReferenceHelper.php b/src/PhpSpreadsheet/ReferenceHelper.php
index de9c3f25d..c8acfd8cf 100644
--- a/src/PhpSpreadsheet/ReferenceHelper.php
+++ b/src/PhpSpreadsheet/ReferenceHelper.php
@@ -444,7 +444,7 @@ class ReferenceHelper
                 if ($cell->getDataType() === DataType::TYPE_FORMULA) {
                     // Formula should be adjusted
                     $worksheet->getCell($newCoordinate)
-                        ->setValue($this->updateFormulaReferences($cell->getValue(), $beforeCellAddress, $numberOfColumns, $numberOfRows, $worksheet->getTitle(), true));
+                        ->setValue($this->updateFormulaReferences($cell->getValueString(), $beforeCellAddress, $numberOfColumns, $numberOfRows, $worksheet->getTitle(), true));
                 } else {
                     // Cell value should not be adjusted
                     $worksheet->getCell($newCoordinate)->setValueExplicit($cell->getValue(), $cell->getDataType());
@@ -457,7 +457,7 @@ class ReferenceHelper
                         but we do still need to adjust any formulae in those cells                    */
                 if ($cell->getDataType() === DataType::TYPE_FORMULA) {
                     // Formula should be adjusted
-                    $cell->setValue($this->updateFormulaReferences($cell->getValue(), $beforeCellAddress, $numberOfColumns, $numberOfRows, $worksheet->getTitle(), true));
+                    $cell->setValue($this->updateFormulaReferences($cell->getValueString(), $beforeCellAddress, $numberOfColumns, $numberOfRows, $worksheet->getTitle(), true));
                 }
             }
         }
@@ -897,7 +897,7 @@ class ReferenceHelper
             foreach ($sheet->getCoordinates(false) as $coordinate) {
                 $cell = $sheet->getCell($coordinate);
                 if ($cell->getDataType() === DataType::TYPE_FORMULA) {
-                    $formula = $cell->getValue();
+                    $formula = $cell->getValueString();
                     if (str_contains($formula, $oldName)) {
                         $formula = str_replace("'" . $oldName . "'!", "'" . $newName . "'!", $formula);
                         $formula = str_replace($oldName . '!', $newName . '!', $formula);
diff --git a/src/PhpSpreadsheet/RichText/RichText.php b/src/PhpSpreadsheet/RichText/RichText.php
index 32b3727be..1dc391a6c 100644
--- a/src/PhpSpreadsheet/RichText/RichText.php
+++ b/src/PhpSpreadsheet/RichText/RichText.php
@@ -27,8 +27,8 @@ class RichText implements IComparable, Stringable
         // Rich-Text string attached to cell?
         if ($cell !== null) {
             // Add cell text and style
-            if ($cell->getValue() != '') {
-                $objRun = new Run($cell->getValue());
+            if ($cell->getValueString() !== '') {
+                $objRun = new Run($cell->getValueString());
                 $objRun->setFont(clone $cell->getWorksheet()->getStyle($cell->getCoordinate())->getFont());
                 $this->addText($objRun);
             }
diff --git a/src/PhpSpreadsheet/Shared/Date.php b/src/PhpSpreadsheet/Shared/Date.php
index ed19534de..b8feeb9c2 100644
--- a/src/PhpSpreadsheet/Shared/Date.php
+++ b/src/PhpSpreadsheet/Shared/Date.php
@@ -10,7 +10,6 @@ use PhpOffice\PhpSpreadsheet\Calculation\Functions;
 use PhpOffice\PhpSpreadsheet\Cell\Cell;
 use PhpOffice\PhpSpreadsheet\Exception;
 use PhpOffice\PhpSpreadsheet\Exception as PhpSpreadsheetException;
-use PhpOffice\PhpSpreadsheet\Shared\Date as SharedDate;
 use PhpOffice\PhpSpreadsheet\Style\NumberFormat;
 
 class Date
@@ -64,15 +63,15 @@ class Date
     /**
      * Set the Excel calendar (Windows 1900 or Mac 1904).
      *
-     * @param int $baseYear Excel base date (1900 or 1904)
+     * @param ?int $baseYear Excel base date (1900 or 1904)
      *
      * @return bool Success or failure
      */
-    public static function setExcelCalendar(int $baseYear): bool
+    public static function setExcelCalendar(?int $baseYear): bool
     {
         if (
-            ($baseYear == self::CALENDAR_WINDOWS_1900)
-            || ($baseYear == self::CALENDAR_MAC_1904)
+            ($baseYear === self::CALENDAR_WINDOWS_1900)
+            || ($baseYear === self::CALENDAR_MAC_1904)
         ) {
             self::$excelCalendar = $baseYear;
 
@@ -173,7 +172,7 @@ class Date
             throw new Exception("Invalid string $value supplied for datatype Date");
         }
 
-        $newValue = SharedDate::PHPToExcel($date);
+        $newValue = self::PHPToExcel($date);
         if ($newValue === false) {
             throw new Exception("Invalid string $value supplied for datatype Date");
         }
diff --git a/src/PhpSpreadsheet/Shared/Trend/PolynomialBestFit.php b/src/PhpSpreadsheet/Shared/Trend/PolynomialBestFit.php
index 3abe695fc..911a9c34f 100644
--- a/src/PhpSpreadsheet/Shared/Trend/PolynomialBestFit.php
+++ b/src/PhpSpreadsheet/Shared/Trend/PolynomialBestFit.php
@@ -159,13 +159,15 @@ class PolynomialBestFit extends BestFit
         $coefficients = [];
         for ($i = 0; $i < $C->rows; ++$i) {
             $r = $C->getValue($i + 1, 1); // row and column are origin-1
-            if (abs($r) <= 10 ** (-9)) {
+            if (!is_numeric($r) || abs($r) <= 10 ** (-9)) {
                 $r = 0;
+            } else {
+                $r += 0;
             }
             $coefficients[] = $r;
         }
 
-        $this->intersect = array_shift($coefficients);
+        $this->intersect = (float) array_shift($coefficients);
         // Phpstan is correct
         //* @phpstan-ignore-next-line
         $this->slope = $coefficients;
diff --git a/src/PhpSpreadsheet/Spreadsheet.php b/src/PhpSpreadsheet/Spreadsheet.php
index 095507d7b..e571cc4f6 100644
--- a/src/PhpSpreadsheet/Spreadsheet.php
+++ b/src/PhpSpreadsheet/Spreadsheet.php
@@ -7,6 +7,7 @@ use PhpOffice\PhpSpreadsheet\Calculation\Calculation;
 use PhpOffice\PhpSpreadsheet\Document\Properties;
 use PhpOffice\PhpSpreadsheet\Document\Security;
 use PhpOffice\PhpSpreadsheet\Reader\Xlsx as XlsxReader;
+use PhpOffice\PhpSpreadsheet\Shared\Date;
 use PhpOffice\PhpSpreadsheet\Shared\File;
 use PhpOffice\PhpSpreadsheet\Shared\StringHelper;
 use PhpOffice\PhpSpreadsheet\Style\Style;
@@ -31,6 +32,8 @@ class Spreadsheet implements JsonSerializable
         self::VISIBILITY_VERY_HIDDEN,
     ];
 
+    protected int $excelCalendar = Date::CALENDAR_WINDOWS_1900;
+
     /**
      * Unique ID.
      */
@@ -1553,4 +1556,26 @@ class Spreadsheet implements JsonSerializable
 
         return $table;
     }
+
+    /**
+     * @return bool Success or failure
+     */
+    public function setExcelCalendar(int $baseYear): bool
+    {
+        if (($baseYear === Date::CALENDAR_WINDOWS_1900) || ($baseYear === Date::CALENDAR_MAC_1904)) {
+            $this->excelCalendar = $baseYear;
+
+            return true;
+        }
+
+        return false;
+    }
+
+    /**
+     * @return int Excel base date (1900 or 1904)
+     */
+    public function getExcelCalendar(): int
+    {
+        return $this->excelCalendar;
+    }
 }
diff --git a/src/PhpSpreadsheet/Writer/Csv.php b/src/PhpSpreadsheet/Writer/Csv.php
index 6e0c20d25..d15bc654c 100644
--- a/src/PhpSpreadsheet/Writer/Csv.php
+++ b/src/PhpSpreadsheet/Writer/Csv.php
@@ -3,6 +3,7 @@
 namespace PhpOffice\PhpSpreadsheet\Writer;
 
 use PhpOffice\PhpSpreadsheet\Calculation\Calculation;
+use PhpOffice\PhpSpreadsheet\Cell\Coordinate;
 use PhpOffice\PhpSpreadsheet\Spreadsheet;
 use Stringable;
 
@@ -54,6 +55,13 @@ class Csv extends BaseWriter
      */
     private string $outputEncoding = '';
 
+    /**
+     * Whether number of columns should be allowed to vary
+     * between rows, or use a fixed range based on the max
+     * column overall.
+     */
+    private bool $variableColumns = false;
+
     /**
      * Create a new CSV.
      */
@@ -104,7 +112,17 @@ class Csv extends BaseWriter
         $maxRow = $sheet->getHighestDataRow();
 
         // Write rows to file
+        $row = 0;
         foreach ($sheet->rangeToArrayYieldRows("A1:$maxCol$maxRow", '', $this->preCalculateFormulas) as $cellsArray) {
+            ++$row;
+            if ($this->variableColumns) {
+                $column = $sheet->getHighestDataColumn($row);
+                if ($column === 'A' && !$sheet->cellExists("A$row")) {
+                    $cellsArray = [];
+                } else {
+                    array_splice($cellsArray, Coordinate::columnIndexFromString($column));
+                }
+            }
             $this->writeLine($this->fileHandle, $cellsArray);
         }
 
@@ -301,4 +319,26 @@ class Csv extends BaseWriter
         }
         fwrite($fileHandle, $line);
     }
+
+    /**
+     * Get whether number of columns should be allowed to vary
+     * between rows, or use a fixed range based on the max
+     * column overall.
+     */
+    public function getVariableColumns(): bool
+    {
+        return $this->variableColumns;
+    }
+
+    /**
+     * Set whether number of columns should be allowed to vary
+     * between rows, or use a fixed range based on the max
+     * column overall.
+     */
+    public function setVariableColumns(bool $pValue): self
+    {
+        $this->variableColumns = $pValue;
+
+        return $this;
+    }
 }
diff --git a/src/PhpSpreadsheet/Writer/Html.php b/src/PhpSpreadsheet/Writer/Html.php
index d7a52e65b..1dfd8c0bf 100644
--- a/src/PhpSpreadsheet/Writer/Html.php
+++ b/src/PhpSpreadsheet/Writer/Html.php
@@ -6,6 +6,7 @@ use PhpOffice\PhpSpreadsheet\Calculation\Calculation;
 use PhpOffice\PhpSpreadsheet\Cell\Cell;
 use PhpOffice\PhpSpreadsheet\Cell\Coordinate;
 use PhpOffice\PhpSpreadsheet\Chart\Chart;
+use PhpOffice\PhpSpreadsheet\Comment;
 use PhpOffice\PhpSpreadsheet\Document\Properties;
 use PhpOffice\PhpSpreadsheet\RichText\RichText;
 use PhpOffice\PhpSpreadsheet\RichText\Run;
@@ -1763,9 +1764,15 @@ class Html extends BaseWriter
         $result = '';
         if (!$this->isPdf && isset($worksheet->getComments()[$coordinate])) {
             $sanitizedString = $this->generateRowCellDataValueRich($worksheet->getComment($coordinate)->getText());
+            $dir = ($worksheet->getComment($coordinate)->getTextboxDirection() === Comment::TEXTBOX_DIRECTION_RTL) ? ' dir="rtl"' : '';
+            $align = strtolower($worksheet->getComment($coordinate)->getAlignment());
+            $alignment = Alignment::HORIZONTAL_ALIGNMENT_FOR_HTML[$align] ?? '';
+            if ($alignment !== '') {
+                $alignment = " style=\"text-align:$alignment\"";
+            }
             if ($sanitizedString !== '') {
                 $result .= '<a class="comment-indicator"></a>';
-                $result .= '<div class="comment">' . $sanitizedString . '</div>';
+                $result .= "<div class=\"comment\"$dir$alignment>" . $sanitizedString . '</div>';
                 $result .= PHP_EOL;
             }
         }
diff --git a/src/PhpSpreadsheet/Writer/Xls/Workbook.php b/src/PhpSpreadsheet/Writer/Xls/Workbook.php
index 62d4b08d9..a1a5faf8f 100644
--- a/src/PhpSpreadsheet/Writer/Xls/Workbook.php
+++ b/src/PhpSpreadsheet/Writer/Xls/Workbook.php
@@ -910,9 +910,9 @@ class Workbook extends BIFFwriter
         $record = 0x0022; // Record identifier
         $length = 0x0002; // Bytes to follow
 
-        $f1904 = (Date::getExcelCalendar() === Date::CALENDAR_MAC_1904)
-            ? 1
-            : 0; // Flag for 1904 date system
+        $f1904 = ($this->spreadsheet->getExcelCalendar() === Date::CALENDAR_MAC_1904)
+            ? 1  // Flag for 1904 date system
+            : 0; // Flag for 1900 date system
 
         $header = pack('vv', $record, $length);
         $data = pack('v', $f1904);
diff --git a/src/PhpSpreadsheet/Writer/Xlsx/Comments.php b/src/PhpSpreadsheet/Writer/Xlsx/Comments.php
index f64542197..f42c2427b 100644
--- a/src/PhpSpreadsheet/Writer/Xlsx/Comments.php
+++ b/src/PhpSpreadsheet/Writer/Xlsx/Comments.php
@@ -209,12 +209,14 @@ class Comments extends WriterPart
         $objWriter->endElement();
 
         // v:textbox
+        $textBoxArray = [Comment::TEXTBOX_DIRECTION_RTL => 'rtl', Comment::TEXTBOX_DIRECTION_LTR => 'ltr'];
+        $textboxRtl = $textBoxArray[strtolower($comment->getTextBoxDirection())] ?? 'auto';
         $objWriter->startElement('v:textbox');
-        $objWriter->writeAttribute('style', 'mso-direction-alt:auto');
+        $objWriter->writeAttribute('style', "mso-direction-alt:$textboxRtl");
 
         // div
         $objWriter->startElement('div');
-        $objWriter->writeAttribute('style', 'text-align:left');
+        $objWriter->writeAttribute('style', ($textboxRtl === 'rtl' ? 'text-align:right;direction:rtl' : 'text-align:left'));
         $objWriter->endElement();
 
         $objWriter->endElement();
diff --git a/src/PhpSpreadsheet/Writer/Xlsx/Workbook.php b/src/PhpSpreadsheet/Writer/Xlsx/Workbook.php
index 5604be544..0cdfb3cd8 100644
--- a/src/PhpSpreadsheet/Writer/Xlsx/Workbook.php
+++ b/src/PhpSpreadsheet/Writer/Xlsx/Workbook.php
@@ -40,7 +40,7 @@ class Workbook extends WriterPart
         $this->writeFileVersion($objWriter);
 
         // workbookPr
-        $this->writeWorkbookPr($objWriter);
+        $this->writeWorkbookPr($objWriter, $spreadsheet);
 
         // workbookProtection
         $this->writeWorkbookProtection($objWriter, $spreadsheet);
@@ -81,11 +81,11 @@ class Workbook extends WriterPart
     /**
      * Write WorkbookPr.
      */
-    private function writeWorkbookPr(XMLWriter $objWriter): void
+    private function writeWorkbookPr(XMLWriter $objWriter, Spreadsheet $spreadsheet): void
     {
         $objWriter->startElement('workbookPr');
 
-        if (Date::getExcelCalendar() === Date::CALENDAR_MAC_1904) {
+        if ($spreadsheet->getExcelCalendar() === Date::CALENDAR_MAC_1904) {
             $objWriter->writeAttribute('date1904', '1');
         }
 
diff --git a/tests/PhpSpreadsheetTests/Cell/CellTest.php b/tests/PhpSpreadsheetTests/Cell/CellTest.php
index 8bd4b9f8f..0a4308b61 100644
--- a/tests/PhpSpreadsheetTests/Cell/CellTest.php
+++ b/tests/PhpSpreadsheetTests/Cell/CellTest.php
@@ -19,16 +19,20 @@ use PHPUnit\Framework\TestCase;
 
 class CellTest extends TestCase
 {
+    private ?Spreadsheet $spreadsheet = null;
+
     protected function setUp(): void
     {
-        parent::setUp();
         Cell::setValueBinder(new DefaultValueBinder());
     }
 
     protected function tearDown(): void
     {
-        parent::tearDown();
         Cell::setValueBinder(new DefaultValueBinder());
+        if ($this->spreadsheet !== null) {
+            $this->spreadsheet->disconnectWorksheets();
+            $this->spreadsheet = null;
+        }
     }
 
     public function testSetValueBinderOverride(): void
@@ -92,15 +96,13 @@ class CellTest extends TestCase
 
     public function testInvalidIsoDateSetValueExplicit(): void
     {
-        $spreadsheet = new Spreadsheet();
-        $cell = $spreadsheet->getActiveSheet()->getCell('A1');
+        $this->spreadsheet = new Spreadsheet();
+        $cell = $this->spreadsheet->getActiveSheet()->getCell('A1');
 
         $dateValue = '2022-02-29'; // Invalid leap year
         $this->expectException(Exception::class);
         $this->expectExceptionMessage("Invalid string {$dateValue} supplied for datatype Date");
         $cell->setValueExplicit($dateValue, DataType::TYPE_ISO_DATE);
-
-        $spreadsheet->disconnectWorksheets();
     }
 
     /**
@@ -110,8 +112,8 @@ class CellTest extends TestCase
     {
         $this->expectException(Exception::class);
 
-        $spreadsheet = new Spreadsheet();
-        $cell = $spreadsheet->getActiveSheet()->getCell('A1');
+        $this->spreadsheet = new Spreadsheet();
+        $cell = $this->spreadsheet->getActiveSheet()->getCell('A1');
         $cell->setValueExplicit($value, $dataType);
     }
 
@@ -166,8 +168,8 @@ class CellTest extends TestCase
 
     public function testDestroyCell2(): void
     {
-        $spreadsheet = new Spreadsheet();
-        $sheet = $spreadsheet->getActiveSheet();
+        $this->spreadsheet = new Spreadsheet();
+        $sheet = $this->spreadsheet->getActiveSheet();
         $cell = $sheet->getCell('A1');
         self::assertSame('A1', $cell->getCoordinate());
         $this->expectException(Exception::class);
@@ -245,6 +247,7 @@ class CellTest extends TestCase
             $greenStyle->getFill()->getStartColor()->getARGB(),
             $style->getFill()->getStartColor()->getARGB()
         );
+        $spreadsheet->disconnectWorksheets();
     }
 
     /**
@@ -296,6 +299,7 @@ class CellTest extends TestCase
         if ($fillStyle === Fill::FILL_SOLID) {
             self::assertEquals($fillColor, $style->getFill()->getStartColor()->getARGB());
         }
+        $spreadsheet->disconnectWorksheets();
     }
 
     public static function appliedStyling(): array
diff --git a/tests/PhpSpreadsheetTests/Cell/DefaultValueBinderTest.php b/tests/PhpSpreadsheetTests/Cell/DefaultValueBinderTest.php
index fb9b42dbe..8cb5d8876 100644
--- a/tests/PhpSpreadsheetTests/Cell/DefaultValueBinderTest.php
+++ b/tests/PhpSpreadsheetTests/Cell/DefaultValueBinderTest.php
@@ -108,4 +108,27 @@ class DefaultValueBinderTest extends TestCase
         self::assertTrue($binder::$called);
         $spreadsheet->disconnectWorksheets();
     }
+
+    public function testDataTypeForValueExceptions(): void
+    {
+        try {
+            self::assertSame('s', DefaultValueBinder::dataTypeForValue(new SpreadsheetException()));
+        } catch (SpreadsheetException $e) {
+            self::fail('Should not have failed for stringable');
+        }
+
+        try {
+            DefaultValueBinder::dataTypeForValue([]);
+            self::fail('Should have failed for array');
+        } catch (SpreadsheetException $e) {
+            self::assertStringContainsString('unusable type array', $e->getMessage());
+        }
+
+        try {
+            DefaultValueBinder::dataTypeForValue(new DateTime());
+            self::fail('Should have failed for DateTime');
+        } catch (SpreadsheetException $e) {
+            self::assertStringContainsString('unusable type DateTime', $e->getMessage());
+        }
+    }
 }
diff --git a/tests/PhpSpreadsheetTests/Reader/Xls/DateReaderTest.php b/tests/PhpSpreadsheetTests/Reader/Xls/DateReaderTest.php
new file mode 100644
index 000000000..58bcbb95b
--- /dev/null
+++ b/tests/PhpSpreadsheetTests/Reader/Xls/DateReaderTest.php
@@ -0,0 +1,127 @@
+<?php
+
+namespace PhpOffice\PhpSpreadsheetTests\Reader\Xls;
+
+use PhpOffice\PhpSpreadsheet\Reader\Xls;
+use PhpOffice\PhpSpreadsheet\Shared\Date;
+use PHPUnit\Framework\TestCase;
+
+class DateReaderTest extends TestCase
+{
+    protected function tearDown(): void
+    {
+        Date::setExcelCalendar(Date::CALENDAR_WINDOWS_1900);
+    }
+
+    public function testReadExcel1900Spreadsheet(): void
+    {
+        $filename = 'tests/data/Reader/XLS/1900_Calendar.xls';
+        $reader = new Xls();
+        $spreadsheet = $reader->load($filename);
+
+        self::assertSame(Date::CALENDAR_WINDOWS_1900, $spreadsheet->getExcelCalendar());
+
+        $worksheet = $spreadsheet->getActiveSheet();
+        self::assertSame(44562, $worksheet->getCell('A1')->getValue());
+        self::assertSame('2022-01-01', $worksheet->getCell('A1')->getFormattedValue());
+        self::assertSame(44926, $worksheet->getCell('A2')->getValue());
+        self::assertSame('2022-12-31', $worksheet->getCell('A2')->getFormattedValue());
+        $spreadsheet->disconnectWorksheets();
+    }
+
+    public function testReadExcel1904Spreadsheet(): void
+    {
+        $filename = 'tests/data/Reader/XLS/1904_Calendar.xls';
+        $reader = new Xls();
+        $spreadsheet = $reader->load($filename);
+
+        self::assertSame(Date::CALENDAR_MAC_1904, $spreadsheet->getExcelCalendar());
+
+        $worksheet = $spreadsheet->getActiveSheet();
+        self::assertSame(43100, $worksheet->getCell('A1')->getValue());
+        self::assertSame('2022-01-01', $worksheet->getCell('A1')->getFormattedValue());
+        self::assertSame(43464, $worksheet->getCell('A2')->getValue());
+        self::assertSame('2022-12-31', $worksheet->getCell('A2')->getFormattedValue());
+        $spreadsheet->disconnectWorksheets();
+    }
+
+    public function testNewDateInLoadedExcel1900Spreadsheet(): void
+    {
+        $filename = 'tests/data/Reader/XLS/1900_Calendar.xls';
+        $reader = new Xls();
+        $spreadsheet = $reader->load($filename);
+
+        $worksheet = $spreadsheet->getActiveSheet();
+        $worksheet->getCell('A4')->setValue('=DATE(2023,1,1)');
+        self::assertEquals(44927, $worksheet->getCell('A4')->getCalculatedValue());
+        $spreadsheet->disconnectWorksheets();
+    }
+
+    public function testNewDateInLoadedExcel1904Spreadsheet(): void
+    {
+        $filename = 'tests/data/Reader/XLS/1904_Calendar.xls';
+        $reader = new Xls();
+        $spreadsheet = $reader->load($filename);
+
+        $worksheet = $spreadsheet->getActiveSheet();
+        $worksheet->getCell('A4')->setValue('=DATE(2023,1,1)');
+        self::assertEquals(43465, $worksheet->getCell('A4')->getCalculatedValue());
+        $spreadsheet->disconnectWorksheets();
+    }
+
+    public function testSwitchCalendars(): void
+    {
+        $filename1904 = 'tests/data/Reader/XLS/1904_Calendar.xls';
+        $reader1904 = new Xls();
+        $spreadsheet1904 = $reader1904->load($filename1904);
+        $worksheet1904 = $spreadsheet1904->getActiveSheet();
+        $date1 = Date::convertIsoDate('2022-01-01');
+        self::assertSame(43100.0, $date1);
+
+        $filename1900 = 'tests/data/Reader/XLS/1900_Calendar.xls';
+        $reader1900 = new Xls();
+        $spreadsheet1900 = $reader1900->load($filename1900);
+        $worksheet1900 = $spreadsheet1900->getActiveSheet();
+        $date2 = Date::convertIsoDate('2022-01-01');
+        self::assertSame(44562.0, $date2);
+
+        self::assertSame(44562, $worksheet1900->getCell('A1')->getValue());
+        self::assertSame('2022-01-01', $worksheet1900->getCell('A1')->getFormattedValue());
+        self::assertSame(44926, $worksheet1900->getCell('A2')->getValue());
+        self::assertSame('2022-12-31', $worksheet1900->getCell('A2')->getFormattedValue());
+        self::assertSame(44561, $worksheet1900->getCell('B1')->getCalculatedValue());
+        self::assertSame('2021-12-31', $worksheet1900->getCell('B1')->getFormattedValue());
+        self::assertSame(44927, $worksheet1900->getCell('B2')->getCalculatedValue());
+        self::assertSame('2023-01-01', $worksheet1900->getCell('B2')->getFormattedValue());
+
+        self::assertSame(43100, $worksheet1904->getCell('A1')->getValue());
+        self::assertSame('2022-01-01', $worksheet1904->getCell('A1')->getFormattedValue());
+        self::assertSame(43464, $worksheet1904->getCell('A2')->getValue());
+        self::assertSame('2022-12-31', $worksheet1904->getCell('A2')->getFormattedValue());
+        self::assertSame(43099, $worksheet1904->getCell('B1')->getCalculatedValue());
+        self::assertSame('2021-12-31', $worksheet1904->getCell('B1')->getFormattedValue());
+        self::assertSame(43465, $worksheet1904->getCell('B2')->getCalculatedValue());
+        self::assertSame('2023-01-01', $worksheet1904->getCell('B2')->getFormattedValue());
+
+        // Check that accessing date values from one spreadsheet doesn't break accessing correct values from another
+        self::assertSame(44561, $worksheet1900->getCell('B1')->getCalculatedValue());
+        self::assertSame('2021-12-31', $worksheet1900->getCell('B1')->getFormattedValue());
+        self::assertSame(44927, $worksheet1900->getCell('B2')->getCalculatedValue());
+        self::assertSame('2023-01-01', $worksheet1900->getCell('B2')->getFormattedValue());
+        self::assertSame(44562, $worksheet1900->getCell('A1')->getValue());
+        self::assertSame('2022-01-01', $worksheet1900->getCell('A1')->getFormattedValue());
+        self::assertSame(44926, $worksheet1900->getCell('A2')->getValue());
+        self::assertSame('2022-12-31', $worksheet1900->getCell('A2')->getFormattedValue());
+
+        self::assertSame(43099, $worksheet1904->getCell('B1')->getCalculatedValue());
+        self::assertSame('2021-12-31', $worksheet1904->getCell('B1')->getFormattedValue());
+        self::assertSame(43465, $worksheet1904->getCell('B2')->getCalculatedValue());
+        self::assertSame('2023-01-01', $worksheet1904->getCell('B2')->getFormattedValue());
+        self::assertSame(43100, $worksheet1904->getCell('A1')->getValue());
+        self::assertSame('2022-01-01', $worksheet1904->getCell('A1')->getFormattedValue());
+        self::assertSame(43464, $worksheet1904->getCell('A2')->getValue());
+        self::assertSame('2022-12-31', $worksheet1904->getCell('A2')->getFormattedValue());
+        $spreadsheet1900->disconnectWorksheets();
+        $spreadsheet1904->disconnectWorksheets();
+    }
+}
diff --git a/tests/PhpSpreadsheetTests/Reader/Xlsx/DateReaderTest.php b/tests/PhpSpreadsheetTests/Reader/Xlsx/DateReaderTest.php
new file mode 100644
index 000000000..7eaee0df7
--- /dev/null
+++ b/tests/PhpSpreadsheetTests/Reader/Xlsx/DateReaderTest.php
@@ -0,0 +1,135 @@
+<?php
+
+namespace PhpOffice\PhpSpreadsheetTests\Reader\Xlsx;
+
+use PhpOffice\PhpSpreadsheet\Reader\Xlsx;
+use PhpOffice\PhpSpreadsheet\Shared\Date;
+use PHPUnit\Framework\TestCase;
+
+class DateReaderTest extends TestCase
+{
+    protected function tearDown(): void
+    {
+        Date::setExcelCalendar(Date::CALENDAR_WINDOWS_1900);
+    }
+
+    public function testReadExcel1900Spreadsheet(): void
+    {
+        $filename = 'tests/data/Reader/XLSX/1900_Calendar.xlsx';
+        $reader = new Xlsx();
+        $spreadsheet = $reader->load($filename);
+
+        self::assertSame(Date::CALENDAR_WINDOWS_1900, $spreadsheet->getExcelCalendar());
+
+        $worksheet = $spreadsheet->getActiveSheet();
+        self::assertSame(44562, $worksheet->getCell('A1')->getValue());
+        self::assertSame('2022-01-01', $worksheet->getCell('A1')->getFormattedValue());
+        self::assertSame(44926, $worksheet->getCell('A2')->getValue());
+        self::assertSame('2022-12-31', $worksheet->getCell('A2')->getFormattedValue());
+        self::assertSame(44561, $worksheet->getCell('B1')->getCalculatedValue());
+        self::assertSame('2021-12-31', $worksheet->getCell('B1')->getFormattedValue());
+        self::assertSame(44927, $worksheet->getCell('B2')->getCalculatedValue());
+        self::assertSame('2023-01-01', $worksheet->getCell('B2')->getFormattedValue());
+        $spreadsheet->disconnectWorksheets();
+    }
+
+    public function testReadExcel1904Spreadsheet(): void
+    {
+        $filename = 'tests/data/Reader/XLSX/1904_Calendar.xlsx';
+        $reader = new Xlsx();
+        $spreadsheet = $reader->load($filename);
+
+        self::assertSame(Date::CALENDAR_MAC_1904, $spreadsheet->getExcelCalendar());
+
+        $worksheet = $spreadsheet->getActiveSheet();
+        self::assertSame(43100, $worksheet->getCell('A1')->getValue());
+        self::assertSame('2022-01-01', $worksheet->getCell('A1')->getFormattedValue());
+        self::assertSame(43464, $worksheet->getCell('A2')->getValue());
+        self::assertSame('2022-12-31', $worksheet->getCell('A2')->getFormattedValue());
+        self::assertSame(43099, $worksheet->getCell('B1')->getCalculatedValue());
+        self::assertSame('2021-12-31', $worksheet->getCell('B1')->getFormattedValue());
+        self::assertSame(43465, $worksheet->getCell('B2')->getCalculatedValue());
+        self::assertSame('2023-01-01', $worksheet->getCell('B2')->getFormattedValue());
+        $spreadsheet->disconnectWorksheets();
+    }
+
+    public function testNewDateInLoadedExcel1900Spreadsheet(): void
+    {
+        $filename = 'tests/data/Reader/XLSX/1900_Calendar.xlsx';
+        $reader = new Xlsx();
+        $spreadsheet = $reader->load($filename);
+
+        $worksheet = $spreadsheet->getActiveSheet();
+        $worksheet->getCell('A4')->setValue('=DATE(2023,1,1)');
+        self::assertEquals(44927, $worksheet->getCell('A4')->getCalculatedValue());
+        $spreadsheet->disconnectWorksheets();
+    }
+
+    public function testNewDateInLoadedExcel1904Spreadsheet(): void
+    {
+        $filename = 'tests/data/Reader/XLSX/1904_Calendar.xlsx';
+        $reader = new Xlsx();
+        $spreadsheet = $reader->load($filename);
+
+        $worksheet = $spreadsheet->getActiveSheet();
+        $worksheet->getCell('A4')->setValue('=DATE(2023,1,1)');
+        self::assertEquals(43465, $worksheet->getCell('A4')->getCalculatedValue());
+        $spreadsheet->disconnectWorksheets();
+    }
+
+    public function testSwitchCalendars(): void
+    {
+        $filename1904 = 'tests/data/Reader/XLSX/1904_Calendar.xlsx';
+        $reader1904 = new Xlsx();
+        $spreadsheet1904 = $reader1904->load($filename1904);
+        $worksheet1904 = $spreadsheet1904->getActiveSheet();
+        $date1 = Date::convertIsoDate('2022-01-01');
+        self::assertSame(43100.0, $date1);
+
+        $filename1900 = 'tests/data/Reader/XLSX/1900_Calendar.xlsx';
+        $reader1900 = new Xlsx();
+        $spreadsheet1900 = $reader1900->load($filename1900);
+        $worksheet1900 = $spreadsheet1900->getActiveSheet();
+        $date2 = Date::convertIsoDate('2022-01-01');
+        self::assertSame(44562.0, $date2);
+
+        self::assertSame(44562, $worksheet1900->getCell('A1')->getValue());
+        self::assertSame('2022-01-01', $worksheet1900->getCell('A1')->getFormattedValue());
+        self::assertSame(44926, $worksheet1900->getCell('A2')->getValue());
+        self::assertSame('2022-12-31', $worksheet1900->getCell('A2')->getFormattedValue());
+        self::assertSame(44561, $worksheet1900->getCell('B1')->getCalculatedValue());
+        self::assertSame('2021-12-31', $worksheet1900->getCell('B1')->getFormattedValue());
+        self::assertSame(44927, $worksheet1900->getCell('B2')->getCalculatedValue());
+        self::assertSame('2023-01-01', $worksheet1900->getCell('B2')->getFormattedValue());
+
+        self::assertSame(43100, $worksheet1904->getCell('A1')->getValue());
+        self::assertSame('2022-01-01', $worksheet1904->getCell('A1')->getFormattedValue());
+        self::assertSame(43464, $worksheet1904->getCell('A2')->getValue());
+        self::assertSame('2022-12-31', $worksheet1904->getCell('A2')->getFormattedValue());
+        self::assertSame(43099, $worksheet1904->getCell('B1')->getCalculatedValue());
+        self::assertSame('2021-12-31', $worksheet1904->getCell('B1')->getFormattedValue());
+        self::assertSame(43465, $worksheet1904->getCell('B2')->getCalculatedValue());
+        self::assertSame('2023-01-01', $worksheet1904->getCell('B2')->getFormattedValue());
+
+        // Check that accessing date values from one spreadsheet doesn't break accessing correct values from another
+        self::assertSame(44561, $worksheet1900->getCell('B1')->getCalculatedValue());
+        self::assertSame('2021-12-31', $worksheet1900->getCell('B1')->getFormattedValue());
+        self::assertSame(44927, $worksheet1900->getCell('B2')->getCalculatedValue());
+        self::assertSame('2023-01-01', $worksheet1900->getCell('B2')->getFormattedValue());
+        self::assertSame(44562, $worksheet1900->getCell('A1')->getValue());
+        self::assertSame('2022-01-01', $worksheet1900->getCell('A1')->getFormattedValue());
+        self::assertSame(44926, $worksheet1900->getCell('A2')->getValue());
+        self::assertSame('2022-12-31', $worksheet1900->getCell('A2')->getFormattedValue());
+
+        self::assertSame(43099, $worksheet1904->getCell('B1')->getCalculatedValue());
+        self::assertSame('2021-12-31', $worksheet1904->getCell('B1')->getFormattedValue());
+        self::assertSame(43465, $worksheet1904->getCell('B2')->getCalculatedValue());
+        self::assertSame('2023-01-01', $worksheet1904->getCell('B2')->getFormattedValue());
+        self::assertSame(43100, $worksheet1904->getCell('A1')->getValue());
+        self::assertSame('2022-01-01', $worksheet1904->getCell('A1')->getFormattedValue());
+        self::assertSame(43464, $worksheet1904->getCell('A2')->getValue());
+        self::assertSame('2022-12-31', $worksheet1904->getCell('A2')->getFormattedValue());
+        $spreadsheet1900->disconnectWorksheets();
+        $spreadsheet1904->disconnectWorksheets();
+    }
+}
diff --git a/tests/PhpSpreadsheetTests/Reader/Xlsx/Issue4063Test.php b/tests/PhpSpreadsheetTests/Reader/Xlsx/Issue4063Test.php
new file mode 100644
index 000000000..d30503ae1
--- /dev/null
+++ b/tests/PhpSpreadsheetTests/Reader/Xlsx/Issue4063Test.php
@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpOffice\PhpSpreadsheetTests\Reader\Xlsx;
+
+use PhpOffice\PhpSpreadsheet\IOFactory;
+use PHPUnit\Framework\TestCase;
+
+class Issue4063Test extends TestCase
+{
+    private static string $testbook = 'tests/data/Reader/XLSX/issue.4063.xlsx';
+
+    public function testSharedStringsWithEmptyString(): void
+    {
+        $spreadsheet = IOFactory::load(self::$testbook);
+        $sheet = $spreadsheet->getActiveSheet();
+        $data = $sheet->toArray(null, true, true, true);
+        $nbsp = "\u{00a0}";
+        self::assertSame(['A' => '226', 'B' => '', 'C' => $nbsp], $data[17]);
+        self::assertSame(['A' => '38873', 'B' => 'gg', 'C' => ' '], $data[22]);
+        $spreadsheet->disconnectWorksheets();
+    }
+}
diff --git a/tests/PhpSpreadsheetTests/Writer/Csv/VariableColumnsTest.php b/tests/PhpSpreadsheetTests/Writer/Csv/VariableColumnsTest.php
new file mode 100644
index 000000000..2d7270814
--- /dev/null
+++ b/tests/PhpSpreadsheetTests/Writer/Csv/VariableColumnsTest.php
@@ -0,0 +1,81 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpOffice\PhpSpreadsheetTests\Writer\Csv;
+
+use PhpOffice\PhpSpreadsheet\Shared\File;
+use PhpOffice\PhpSpreadsheet\Spreadsheet;
+use PhpOffice\PhpSpreadsheet\Writer\Csv;
+use PHPUnit\Framework\TestCase;
+
+class VariableColumnsTest extends TestCase
+{
+    public function testVariableColumns(): void
+    {
+        $spreadsheet = new Spreadsheet();
+        $sheet = $spreadsheet->getActiveSheet();
+        $sheet->fromArray(
+            [
+                [1, 2, 3, 4],
+                [1, 2],
+                [1, 2, 3, 4, 5],
+                [],
+                [1],
+                [1, 2, 3],
+            ]
+        );
+
+        $filename = File::temporaryFilename();
+        $writer = new Csv($spreadsheet);
+        $writer->setVariableColumns(true);
+        $writer->save($filename);
+
+        $contents = (string) file_get_contents($filename);
+        unlink($filename);
+        $spreadsheet->disconnectWorksheets();
+
+        $rows = explode(PHP_EOL, $contents);
+
+        self::assertSame('"1","2","3","4"', $rows[0]);
+        self::assertSame('"1","2"', $rows[1]);
+        self::assertSame('"1","2","3","4","5"', $rows[2]);
+        self::assertSame('', $rows[3]);
+        self::assertSame('"1"', $rows[4]);
+        self::assertSame('"1","2","3"', $rows[5]);
+    }
+
+    public function testFixedColumns(): void
+    {
+        $spreadsheet = new Spreadsheet();
+        $sheet = $spreadsheet->getActiveSheet();
+        $sheet->fromArray(
+            [
+                [1, 2, 3, 4],
+                [1, 2],
+                [1, 2, 3, 4, 5],
+                [],
+                [1],
+                [1, 2, 3],
+            ]
+        );
+
+        $filename = File::temporaryFilename();
+        $writer = new Csv($spreadsheet);
+        self::assertFalse($writer->getVariableColumns());
+        $writer->save($filename);
+
+        $contents = (string) file_get_contents($filename);
+        unlink($filename);
+        $spreadsheet->disconnectWorksheets();
+
+        $rows = explode(PHP_EOL, $contents);
+
+        self::assertSame('"1","2","3","4",""', $rows[0]);
+        self::assertSame('"1","2","","",""', $rows[1]);
+        self::assertSame('"1","2","3","4","5"', $rows[2]);
+        self::assertSame('"","","","",""', $rows[3]);
+        self::assertSame('"1","","","",""', $rows[4]);
+        self::assertSame('"1","2","3","",""', $rows[5]);
+    }
+}
diff --git a/tests/PhpSpreadsheetTests/Writer/Html/CommentAlignmentTest.php b/tests/PhpSpreadsheetTests/Writer/Html/CommentAlignmentTest.php
new file mode 100644
index 000000000..a5f65cbfc
--- /dev/null
+++ b/tests/PhpSpreadsheetTests/Writer/Html/CommentAlignmentTest.php
@@ -0,0 +1,110 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpOffice\PhpSpreadsheetTests\Writer\Html;
+
+use PhpOffice\PhpSpreadsheet\Comment;
+use PhpOffice\PhpSpreadsheet\Spreadsheet;
+use PhpOffice\PhpSpreadsheet\Style\Alignment;
+use PhpOffice\PhpSpreadsheetTests\Functional\AbstractFunctional;
+
+class CommentAlignmentTest extends AbstractFunctional
+{
+    public function testIssue4004(): void
+    {
+        $type = 'Html';
+        $spreadsheet = new Spreadsheet();
+        $sheet = $spreadsheet->getActiveSheet();
+        $sheet->getCell('A3')->setValue('A3');
+        $sheet->getCell('A4')->setValue('A4');
+        $sheet->getComment('A3')->getText()->createText('Comment');
+        $sheet->getComment('A4')->getText()->createText('שלום');
+        $sheet->getComment('A4')->setAlignment(Alignment::HORIZONTAL_RIGHT);
+
+        $reloadedSpreadsheet = $this->writeAndReload($spreadsheet, $type);
+        $spreadsheet->disconnectWorksheets();
+
+        self::assertCount(1, $reloadedSpreadsheet->getAllSheets());
+
+        $rsheet = $reloadedSpreadsheet->getActiveSheet();
+        $comment1 = $rsheet->getComment('A3');
+        self::assertSame('Comment', $comment1->getText()->getPlainText());
+        self::assertSame('general', $comment1->getAlignment());
+        $comment2 = $rsheet->getComment('A4');
+        self::assertSame('שלום', $comment2->getText()->getPlainText());
+        self::assertSame('right', $comment2->getAlignment());
+
+        $reloadedSpreadsheet->disconnectWorksheets();
+    }
+
+    public function testIssue4004td(): void
+    {
+        $type = 'Html';
+        $spreadsheet = new Spreadsheet();
+        $sheet = $spreadsheet->getActiveSheet();
+        $sheet->setRightToLeft(true);
+        $sheet->getCell('A1')->setValue('ברקוד');
+        $comment = $sheet->getComment('A1');
+        $comment->setTextboxDirection(Comment::TEXTBOX_DIRECTION_RTL);
+        $comment->setAlignment(Alignment::HORIZONTAL_RIGHT);
+        $text = <<<EOF
+            Report : ProductsExcel
+            סטטוס הגדרות בזמן הרצת הדו"ח
+
+            2024-06-04 21:07:04
+            תאריך התחלה : 
+            תאריך סיום : 
+            berber@berber.co.il
+
+            הצגת ברקוד מקוצר = 0
+            הצגת חנויות אינטרנט בתוצאות = 1
+
+            הצגת מחיר ליחידת מידה = 0
+            הצגת כל רשומות המחיר לתאריך = 0
+            רשומות עם מחיר בכל הרשתות = 0
+            % נפיצות מינימלית = 0
+            נפיצות מינימלית= 0
+            % נפיצות מקסימלית = 0
+            נפיצות מקסימלית= 0
+            פער אחוזי = 0
+
+            התעלמות מכלל המבצעים = 0
+            התעלמות ממבצעי אשראי = 0
+            התעלמות ממבצעי מועדון = 0
+            התעלמות ממבצעים המותנים בסכום מעל 100 ₪. = 0
+            התעלמות ממבצעים המותנים בקניה של 3 מוצרים ומעלה. = 0
+
+            ניתוח מבצעים
+            ============
+            הצגת כל המבצעים = 0
+            מבצעי מועדון = 0
+            מבצעי אשראי = 0
+            מבצעי ארנק = 0
+            מחיר מוזל = 0
+            X יחידות ב-Y ₪ = 0
+            השני ב = 0
+            X+Y מתנה = 0
+            אחוז הנחה הפעלה = 0
+            אחוז הנחה מספר = 0
+            מוצרים חסרים - הגבלת חודשים - כמות= 0
+            EOF;
+        $comment->getText()->createTextRun($text);
+        $comment->setWidth('300pt');
+        $comment->setHeight('550pt');
+
+        $reloadedSpreadsheet = $this->writeAndReload($spreadsheet, $type);
+        $spreadsheet->disconnectWorksheets();
+
+        self::assertCount(1, $reloadedSpreadsheet->getAllSheets());
+
+        $rsheet = $reloadedSpreadsheet->getActiveSheet();
+        $comment1 = $rsheet->getComment('A1');
+        self::assertSame($text, $comment1->getText()->getPlainText());
+        $comment->setTextboxDirection(Comment::TEXTBOX_DIRECTION_RTL);
+        self::assertSame('right', $comment1->getAlignment());
+        self::assertSame('rtl', $comment1->getTextboxDirection());
+
+        $reloadedSpreadsheet->disconnectWorksheets();
+    }
+}
diff --git a/tests/PhpSpreadsheetTests/Writer/Xlsx/CommentAlignmentTest.php b/tests/PhpSpreadsheetTests/Writer/Xlsx/CommentAlignmentTest.php
index 5f869216f..bd337bc8d 100644
--- a/tests/PhpSpreadsheetTests/Writer/Xlsx/CommentAlignmentTest.php
+++ b/tests/PhpSpreadsheetTests/Writer/Xlsx/CommentAlignmentTest.php
@@ -4,6 +4,7 @@ declare(strict_types=1);
 
 namespace PhpOffice\PhpSpreadsheetTests\Writer\Xlsx;
 
+use PhpOffice\PhpSpreadsheet\Comment;
 use PhpOffice\PhpSpreadsheet\Spreadsheet;
 use PhpOffice\PhpSpreadsheet\Style\Alignment;
 use PhpOffice\PhpSpreadsheetTests\Functional\AbstractFunctional;
@@ -15,6 +16,8 @@ class CommentAlignmentTest extends AbstractFunctional
         $type = 'Xlsx';
         $spreadsheet = new Spreadsheet();
         $sheet = $spreadsheet->getActiveSheet();
+        $sheet->getCell('A3')->setValue('A3');
+        $sheet->getCell('A4')->setValue('A4');
         $sheet->getComment('A3')->getText()->createText('Comment');
         $sheet->getComment('A4')->getText()->createText('שלום');
         $sheet->getComment('A4')->setAlignment(Alignment::HORIZONTAL_RIGHT);
@@ -30,7 +33,77 @@ class CommentAlignmentTest extends AbstractFunctional
         self::assertSame('general', $comment1->getAlignment());
         $comment2 = $rsheet->getComment('A4');
         self::assertSame('שלום', $comment2->getText()->getPlainText());
-        self::assertSame('Right', $comment2->getAlignment());
+        self::assertSame('right', $comment2->getAlignment());
+
+        $reloadedSpreadsheet->disconnectWorksheets();
+    }
+
+    public function testIssue4004td(): void
+    {
+        $type = 'Xlsx';
+        $spreadsheet = new Spreadsheet();
+        $sheet = $spreadsheet->getActiveSheet();
+        $sheet->setRightToLeft(true);
+        $sheet->getCell('A1')->setValue('ברקוד');
+        $comment = $sheet->getComment('A1');
+        $comment->setTextboxDirection(Comment::TEXTBOX_DIRECTION_RTL);
+        $comment->setAlignment(Alignment::HORIZONTAL_RIGHT);
+        $text = <<<EOF
+            Report : ProductsExcel
+            סטטוס הגדרות בזמן הרצת הדו"ח
+
+            2024-06-04 21:07:04
+            תאריך התחלה : 
+            תאריך סיום : 
+            berber@berber.co.il
+
+            הצגת ברקוד מקוצר = 0
+            הצגת חנויות אינטרנט בתוצאות = 1
+
+            הצגת מחיר ליחידת מידה = 0
+            הצגת כל רשומות המחיר לתאריך = 0
+            רשומות עם מחיר בכל הרשתות = 0
+            % נפיצות מינימלית = 0
+            נפיצות מינימלית= 0
+            % נפיצות מקסימלית = 0
+            נפיצות מקסימלית= 0
+            פער אחוזי = 0
+
+            התעלמות מכלל המבצעים = 0
+            התעלמות ממבצעי אשראי = 0
+            התעלמות ממבצעי מועדון = 0
+            התעלמות ממבצעים המותנים בסכום מעל 100 ₪. = 0
+            התעלמות ממבצעים המותנים בקניה של 3 מוצרים ומעלה. = 0
+
+            ניתוח מבצעים
+            ============
+            הצגת כל המבצעים = 0
+            מבצעי מועדון = 0
+            מבצעי אשראי = 0
+            מבצעי ארנק = 0
+            מחיר מוזל = 0
+            X יחידות ב-Y ₪ = 0
+            השני ב = 0
+            X+Y מתנה = 0
+            אחוז הנחה הפעלה = 0
+            אחוז הנחה מספר = 0
+            מוצרים חסרים - הגבלת חודשים - כמות= 0
+            EOF;
+        $comment->getText()->createTextRun($text);
+        $comment->setWidth('300pt');
+        $comment->setHeight('550pt');
+
+        $reloadedSpreadsheet = $this->writeAndReload($spreadsheet, $type);
+        $spreadsheet->disconnectWorksheets();
+
+        self::assertCount(1, $reloadedSpreadsheet->getAllSheets());
+
+        $rsheet = $reloadedSpreadsheet->getActiveSheet();
+        $comment1 = $rsheet->getComment('A1');
+        self::assertSame($text, $comment1->getText()->getPlainText());
+        $comment->setTextboxDirection(Comment::TEXTBOX_DIRECTION_RTL);
+        self::assertSame('right', $comment1->getAlignment());
+        self::assertSame('rtl', $comment1->getTextboxDirection());
 
         $reloadedSpreadsheet->disconnectWorksheets();
     }
diff --git a/tests/data/Cell/SetValueExplicitException.php b/tests/data/Cell/SetValueExplicitException.php
index 6b1508190..d21372bbd 100644
--- a/tests/data/Cell/SetValueExplicitException.php
+++ b/tests/data/Cell/SetValueExplicitException.php
@@ -5,8 +5,7 @@ declare(strict_types=1);
 use PhpOffice\PhpSpreadsheet\Cell\DataType;
 
 return [
-    [
-        'XYZ',
-        DataType::TYPE_NUMERIC,
-    ],
+    'invalid numeric' => ['XYZ', DataType::TYPE_NUMERIC],
+    'invalid array' => [[], DataType::TYPE_STRING],
+    'invalid unstringable object' => [new DateTime(), DataType::TYPE_INLINE],
 ];
diff --git a/tests/data/Reader/XLS/1900_Calendar.xls b/tests/data/Reader/XLS/1900_Calendar.xls
new file mode 100644
index 000000000..714670a7d
Binary files /dev/null and b/tests/data/Reader/XLS/1900_Calendar.xls differ
diff --git a/tests/data/Reader/XLS/1904_Calendar.xls b/tests/data/Reader/XLS/1904_Calendar.xls
new file mode 100644
index 000000000..cde7fc193
Binary files /dev/null and b/tests/data/Reader/XLS/1904_Calendar.xls differ
diff --git a/tests/data/Reader/XLSX/1900_Calendar.xlsx b/tests/data/Reader/XLSX/1900_Calendar.xlsx
new file mode 100644
index 000000000..dfd78efc7
Binary files /dev/null and b/tests/data/Reader/XLSX/1900_Calendar.xlsx differ
diff --git a/tests/data/Reader/XLSX/1904_Calendar.xlsx b/tests/data/Reader/XLSX/1904_Calendar.xlsx
new file mode 100644
index 000000000..f3a8a12d8
Binary files /dev/null and b/tests/data/Reader/XLSX/1904_Calendar.xlsx differ
diff --git a/tests/data/Reader/XLSX/issue.4063.xlsx b/tests/data/Reader/XLSX/issue.4063.xlsx
new file mode 100644
index 000000000..43f3ea6c7
Binary files /dev/null and b/tests/data/Reader/XLSX/issue.4063.xlsx differ