From 8e2cac0b060a89279c65bec6f9f0d939812538f1 Mon Sep 17 00:00:00 2001
From: Lieven De Foor <lieven.de.foor@tvh.com>
Date: Thu, 28 May 2026 14:19:03 +0200
Subject: [PATCH] Fix: ExcelWorksheets.Delete throws NotSupportedException on
 ExcelChartsheet

The Delete method was attempting to access the PivotTables collection on all worksheet types. However, ExcelChartsheet throws NotSupportedException when accessing PivotTables. Added a type guard to skip PivotTable cleanup for chart sheets.
---
 src/EPPlus/ExcelWorksheets.cs                 | 17 +++++----
 .../Issues/ChartSheetDeleteTests.cs           | 35 +++++++++++++++++++
 2 files changed, 45 insertions(+), 7 deletions(-)
 create mode 100644 src/EPPlusTest/Issues/ChartSheetDeleteTests.cs

diff --git a/src/EPPlus/ExcelWorksheets.cs b/src/EPPlus/ExcelWorksheets.cs
index 789e50cf55..9878e1c686 100644
--- a/src/EPPlus/ExcelWorksheets.cs
+++ b/src/EPPlus/ExcelWorksheets.cs
@@ -470,15 +470,18 @@ public void Delete(int Index)
                 worksheet.Drawings.ClearDrawings();
             }
 
-            //Remove all comments
-            if (!(worksheet is ExcelChartsheet) && worksheet.Comments.Count > 0)
+            if (!(worksheet is ExcelChartsheet))
             {
-                worksheet.Comments.Clear();
-            }
+                //Remove all comments
+                if (worksheet.Comments.Count > 0)
+                {
+                    worksheet.Comments.Clear();
+                }
 
-            while(worksheet.PivotTables.Count>0)
-            {
-                worksheet.PivotTables.Delete(worksheet.PivotTables[0]);
+                while (worksheet.PivotTables.Count > 0)
+                {
+                    worksheet.PivotTables.Delete(worksheet.PivotTables[0]);
+                }
             }
             //Delete any parts still with relations to the Worksheet.
             DeleteRelationsAndParts(worksheet.Part);
diff --git a/src/EPPlusTest/Issues/ChartSheetDeleteTests.cs b/src/EPPlusTest/Issues/ChartSheetDeleteTests.cs
new file mode 100644
index 0000000000..8707aa7b6c
--- /dev/null
+++ b/src/EPPlusTest/Issues/ChartSheetDeleteTests.cs
@@ -0,0 +1,35 @@
+/*******************************************************************************
+ * Required Notice: Copyright (C) EPPlus Software AB. 
+ * https://epplussoftware.com
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *******************************************************************************/
+using System;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using OfficeOpenXml;
+using OfficeOpenXml.Drawing.Chart;
+
+namespace EPPlusTest.Issues
+{
+    [TestClass]
+    public class ChartSheetDeleteTests
+    {
+        [TestMethod]
+        public void DeleteChartSheetShouldNotThrowNotSupportedException()
+        {
+            using (var package = new ExcelPackage())
+            {
+                var ws = package.Workbook.Worksheets.Add("Data");
+                var chartSheet = package.Workbook.Worksheets.AddChart("ChartSheet", eChartType.ColumnClustered);
+                
+                // This call previously threw NotSupportedException because it tried to access chartSheet.PivotTables
+                package.Workbook.Worksheets.Delete(chartSheet);
+                
+                Assert.AreEqual(1, package.Workbook.Worksheets.Count);
+            }
+        }
+    }
+}