Fix ChangeDocumentType not removing VBA parts when converting to non-macro type

When changing a macro-enabled document (.docm) to a standard document (.docx)
via ChangeDocumentType(), VBA-related parts (VbaProjectPart, etc.) were carried
over to the new document type. This left orphaned vbaProject content type entries
in [Content_Types].xml, producing a file that could not be opened by some tools
or that silently re-enabled macros in a supposedly non-macro document.

After ChangeDocumentTypeInternal completes, check if the new content type is
non-macro-enabled. If so, remove parts with VBA relationship types
(vbaProject, keyMapCustomizations) from the new main part.

Fixes #618

Author: iamcymentho

src/DocumentFormat.OpenXml/Packaging/TypedPackageFeatureCollection.cs

@@ -3,9 +3,11 @@
 
 using DocumentFormat.OpenXml.Features;
 using System;
+using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.IO.Packaging;
+using System.Linq;
 
 namespace DocumentFormat.OpenXml.Packaging;
 
@@ -96,6 +98,19 @@ void IDocumentTypeFeature<TDocumentType>.ChangeDocumentType(TDocumentType newTyp
         try
         {
             Package.ChangeDocumentTypeInternal(CreateMainPart());
+
+            // When changing from a macro-enabled type to a non-macro type,
+            // remove VBA-related parts that are no longer valid for the new type.
+            // This prevents orphaned vbaProject content type entries in the package.
+            // See: https://github.com/dotnet/Open-XML-SDK/issues/618
+            var newContentType = GetContentType(newType);
+
+            if (newContentType is not null
+                && !newContentType.Contains("macroEnabled", StringComparison.OrdinalIgnoreCase)
+                && MainPart is { } mainPart)
+            {
+                RemoveVbaPartsFromMainPart(mainPart);
+            }
         }
         catch (OpenXmlPackageException e)
         {
@@ -116,5 +131,30 @@ void IDocumentTypeFeature<TDocumentType>.ChangeDocumentType(TDocumentType newTyp
 
     protected abstract TMainPart CreateMainPart();
 
+    /// <summary>
+    /// Removes VBA-related parts (vbaProject, vbaData, keyMapCustomizations) from the main part.
+    /// These parts are specific to macro-enabled document types and must be removed when
+    /// converting to a non-macro type.
+    /// </summary>
+    private static void RemoveVbaPartsFromMainPart(OpenXmlPart mainPart)
+    {
+        // Relationship types for VBA-related parts that should not exist in non-macro documents
+        var vbaRelationshipTypes = new HashSet<string>(StringComparer.Ordinal)
+        {
+            "http://schemas.microsoft.com/office/2006/relationships/vbaProject",
+            "http://schemas.microsoft.com/office/2006/relationships/keyMapCustomizations",
+        };
+
+        var partsToRemove = mainPart.ChildrenRelationshipParts
+            .Where(p => vbaRelationshipTypes.Contains(p.Value.RelationshipType))
+            .Select(p => p.Value)
+            .ToList();
+
+        foreach (var part in partsToRemove)
+        {
+            mainPart.DeletePart(part);
+        }
+    }
+
     bool IKnownDataPartFeature.IsKnown(string relationshipId) => false;
 }

test/DocumentFormat.OpenXml.Tests/DocxTests01.cs

@@ -361,6 +361,53 @@ public void W039_ChangeDocumentType()
             }
         }
 
+        [Fact]
+        public void ChangeDocumentType_MacroEnabledToDocument_RemovesVbaParts()
+        {
+            using var stream = new MemoryStream();
+
+            // Create a macro-enabled document with a VbaProjectPart
+            using (var doc = WordprocessingDocument.Create(stream, WordprocessingDocumentType.MacroEnabledDocument))
+            {
+                var mainPart = doc.AddMainDocumentPart();
+                mainPart.Document = new W.Document(new W.Body(new W.Paragraph(new W.Run(new W.Text("Test")))));
+
+                // Add a VbaProjectPart (the part that causes the issue)
+                mainPart.AddNewPart<VbaProjectPart>();
+
+                Assert.NotNull(mainPart.VbaProjectPart);
+                Assert.Equal(WordprocessingDocumentType.MacroEnabledDocument, doc.DocumentType);
+            }
+
+            // Re-open and change type to a standard document
+            stream.Position = 0;
+
+            using (var doc = WordprocessingDocument.Open(stream, true))
+            {
+                Assert.Equal(WordprocessingDocumentType.MacroEnabledDocument, doc.DocumentType);
+                Assert.NotNull(doc.MainDocumentPart.VbaProjectPart);
+
+                doc.ChangeDocumentType(WordprocessingDocumentType.Document);
+
+                Assert.Equal(WordprocessingDocumentType.Document, doc.DocumentType);
+
+                // After changing to a non-macro type, VbaProjectPart should be removed
+                Assert.Null(doc.MainDocumentPart.VbaProjectPart);
+            }
+
+            // Re-open and verify the VBA content type is not present in the package
+            stream.Position = 0;
+
+            using (var package = Package.Open(stream, FileMode.Open, FileAccess.Read))
+            {
+                var contentTypes = package.GetParts()
+                    .Select(p => p.ContentType)
+                    .ToList();
+
+                Assert.DoesNotContain("application/vnd.ms-office.vbaProject", contentTypes);
+            }
+        }
+
         [Fact]
         public void W038_DocxCreation_Package()
         {