dotnet/wpf · error · XpsSerializationException

SR.ReachSerialization_WrongPropertyTypeForPageContent

Error message

SR.ReachSerialization_WrongPropertyTypeForPageContent

What it means

Async variant of 3735: ReachPageContentSerializerAsync.PersistObjectData throws XpsSerializationException(SR.ReachSerialization_WrongPropertyTypeForPageContent) when the target object of the context is not a PageContent. Only PageContent instances may be pushed onto the async OperationStack with SerializerAction.serializePage.

Solutions

  1. Pass a PageContent to ReachPageContentSerializerAsync
  2. Use the async collection serializer for PageContent collections
  3. Correct the OperationStack context construction so the target is the PageContent node
  4. Add a pre-push type assertion in custom pipeline code

Example fix

// before
((IXpsSerializationManagerAsync)SerializationManager).OperationStack.Push(
    new SerializableObjectContext(fixedPage, "PageContent")); // wrong type
// after
((IXpsSerializationManagerAsync)SerializationManager).OperationStack.Push(
    new SerializableObjectContext((PageContent)target, "PageContent"));
Defensive patterns

Strategy: type-guard

Validate before calling

if (ctx.TargetObject is not PageContent) throw new ArgumentException("Async page serializer requires PageContent");

Type guard

bool IsAsyncPageTarget(SerializableObjectContext c) => c?.TargetObject is PageContent;

Prevention

When it happens

Trigger: Async XPS save where PersistObjectData receives a SerializableObjectContext whose TargetObject is not PageContent — e.g. a FixedPage or collection handed to the async page serializer.

Common situations: Custom async serialization pipelines in XpsSerializationManagerAsync; wrong node pushed to OperationStack; type changes in document-tree walking code.

Understand the failure class

Background: "is not a compatible type" / "cannot merge" errors: when a value's type doesn't match what the library requires — this error's family across 65 libraries.

Related errors

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/248873954c91370c. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/ReachFramework/Serialization/manager/ReachPageContentSerializerAsync.cs:104

        /// </param>
        internal
        override
        void
        PersistObjectData(
            SerializableObjectContext   serializableObjectContext
            )
        {
            if(serializableObjectContext.IsComplexValue)
            {
                ReachSerializerContext context = new ReachSerializerContext(this,
                                                                            serializableObjectContext,
                                                                            SerializerAction.serializePage);

                ((IXpsSerializationManagerAsync)SerializationManager).OperationStack.Push(context);
            }
            else
            {
                throw new XpsSerializationException(SR.ReachSerialization_WrongPropertyTypeForPageContent);
            }
        }

        private
        void
        SerializePage(
            SerializableObjectContext   serializableObjectContext
            )
        {
            FixedPage fixedPage = Toolbox.GetPageRoot(serializableObjectContext.TargetObject);

            if(fixedPage != null)
            {
                ReachSerializer serializer = SerializationManager.GetSerializer(fixedPage);

                if(serializer!=null)
                {
                    XpsSerializationPrintTicketRequiredEventArgs e =

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