dotnet/wpf · error · XpsSerializationException

SR.ReachSerialization_NoSerializer

Error message

SR.ReachSerialization_NoSerializer

What it means

Async NGCSerializationManager.SaveAsXaml, after deciding how to schedule the SaveAsXaml work item, found no serializer registered for the object's type and threw XpsSerializationException(SR.ReachSerialization_NoSerializer). This is the async twin of the synchronous NGCSerializationManager check, hit when GetSerializer returns null for the queued object.

Solutions

1. Pass only FixedDocumentSequence / FixedDocument / FixedPage objects to SaveAsXaml.
2. Register or select the correct serializer for the type before starting the async save.
3. Add a pre-call type check so an actionable exception is raised before work items are queued.

Example fix

// before
asyncManager.SaveAsXaml(unknownObject);
// after
if (unknownObject is FixedDocumentSequence || unknownObject is FixedDocument || unknownObject is FixedPage)
    asyncManager.SaveAsXaml(unknownObject);
else
    throw new NotSupportedException($"No XPS serializer for {unknownObject?.GetType().FullName}");

if (!(obj is FixedDocumentSequence || obj is FixedDocument || obj is FixedPage))
    throw new ArgumentException("Async SaveAsXaml requires a Fixed* type");

static bool HasXpsSerializer(object o) => o is FixedDocumentSequence or FixedDocument or FixedPage;

try { asyncManager.SaveAsXaml(obj); }
catch (XpsSerializationException ex) when (ex.Message.Contains("NoSerializer")) { /* log type name of queued object */ }

When it happens

Trigger: Async SaveAsXaml invoked with an object type for which the serializer registry lookup fails — typically a non-Fixed* type pushed through the async work-item path.

Common situations: Queuing custom document parts to the async pipeline; type mismatches after refactoring (e.g. passing a FixedPage where the manager expected a FixedDocument context).

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• Serialization of this type of object is not supported.
• SR.ReachSerialization_NoSerializer
• SR.ReachSerialization_NotSupported
• Cannot find the appropriate serializer.
• Serialization of this type of object is not supported.

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/373f08286e8ae7cb. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/ReachFramework/Serialization/manager/NGCSerializationManagerAsync.cs:128

                if(reachSerializer != null)
                {
                    //
                    // Prepare the context that is going to be pushed on the stack
                    //
                    SerializationManagerOperationContextStack
                    contextStack = new SerializationManagerOperationContextStack(reachSerializer,
                                                                                 serializedObject);
                    //
                    // At this stage, start calling another method which would peak at the stack
                    //
                    _operationStack.Push(contextStack);

                    PostSerializationTask(new DispatcherOperationCallback(InvokeSaveAsXamlWorkItem));
                }
                else
                {
                    throw new XpsSerializationException(SR.ReachSerialization_NoSerializer);
                }
            }
        }

        internal
        Object
        InvokeSaveAsXamlWorkItem(
            Object arg
            )
        {
            try
            {
                if(!_serializationOperationCanceled)
                {
                    if(_operationStack.Count > 0)
                    {
                        Object objectOnStack = _operationStack.Pop();

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