Visual Studio serialization error when T4 uses DTE to open generated file

Question

We have a C# T4 file named GenerateProxies.tt which calls several command-line codegen utilities. Using the System.Diagnostics Process class, we redirect the standard output

Answer 1

This is not an answer however the OP could not provide the stack trace as requested in the comments.

I have a similar exception being thrown when I try to execute a function in my tt file to write to the Output window (ST is too long for comment)

private void WriteToOutput(string output)
{
      if (_host == null)
        throw new Exception("Host property returned unexpected value (null)");

      EnvDTE.DTE dte = (EnvDTE.DTE)_host.GetService(typeof(EnvDTE.DTE));

      if (dte == null)
        throw new Exception("Unable to retrieve DTE");

      Window window = dte.Windows.Item(EnvDTE.Constants.vsWindowKindOutput);
      window.Activate();

      var outputWindow = (EnvDTE.OutputWindow) window.Object;
      outputWindow.ActivePane.Activate();

      outputWindow.ActivePane.OutputString(output);
      outputWindow.ActivePane.OutputString("\n");
    }

Severity Code Description Project File Line Suppression State Error Running transformation: System.Runtime.Serialization.SerializationException: Type 'Microsoft.VisualStudio.Platform.WindowManagement.DTE.Windows' in Assembly 'Microsoft.VisualStudio.Platform.WindowManagement, Version=15.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' is not marked as serializable.

Server stack trace: at System.Runtime.Serialization.FormatterServices.InternalGetSerializableMembers(RuntimeType type) at System.Runtime.Serialization.FormatterServices.GetSerializableMembers(Type type, StreamingContext context) at System.Runtime.Serialization.Formatters.Binary.WriteObjectInfo.InitMemberInfo() at System.Runtime.Serialization.Formatters.Binary.WriteObjectInfo.InitSerialize(Object obj, ISurrogateSelector surrogateSelector, StreamingContext context, SerObjectInfoInit serObjectInfoInit, IFormatterConverter converter, ObjectWriter objectWriter, SerializationBinder binder) at System.Runtime.Serialization.Formatters.Binary.WriteObjectInfo.Serialize(Object obj, ISurrogateSelector surrogateSelector, StreamingContext context, SerObjectInfoInit serObjectInfoInit, IFormatterConverter converter, ObjectWriter objectWriter, SerializationBinder binder) at System.Runtime.Serialization.Formatters.Binary.ObjectWriter.Serialize(Object graph, Header[] inHeaders, __BinaryWriter serWriter, Boolean fCheck)
at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Serialize(Stream serializationStream, Object graph, Header[] headers, Boolean fCheck)
at System.Runtime.Remoting.Channels.CrossAppDomainSerializer.SerializeMessageParts(ArrayList argsToSerialize) at System.Runtime.Remoting.Messaging.SmuggledMethodReturnMessage..ctor(IMethodReturnMessage mrm) at System.Runtime.Remoting.Messaging.SmuggledMethodReturnMessage.SmuggleIfPossible(IMessage msg) at System.Runtime.Remoting.Channels.CrossAppDomainSink.DoDispatch(Byte[] reqStmBuff, SmuggledMethodCallMessage smuggledMcm, SmuggledMethodReturnMessage& smuggledMrm) at System.Runtime.Remoting.Channels.CrossAppDomainSink.DoTransitionDispatchCallback(Object[] args)

Exception rethrown at [0]: at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg) at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type) at EnvDTE._DTE.get_Windows() at Microsoft.VisualStudio.TextTemplating8CBB5A87F4A34D52835396F51C533E1D8E9F22BC6977A9510B46C012D01E08C8AD263AC5BA030600D92BC0F39E7F1C3B6AA67D8CE545627E10A7F993E06C0D02.GeneratedTextTransformation.TypeMapper.WriteToOutput(String output) in C:\ViewModels\BaseGridViewModels\BaseViewModels.tt:line 581 at Microsoft.VisualStudio.TextTemplating8CBB5A87F4A34D52835396F51C533E1D8E9F22BC6977A9510B46C012D01E08C8AD263AC5BA030600D92BC0F39E7F1C3B6AA67D8CE545627E10A7F993E06C0D02.GeneratedTextTransformation.TypeMapper.GetItemsToGenerate[T](IEnumerable`1 itemCollection) in C:\ViewModels\BaseGridViewModels\BaseViewModels.tt:line 566 at Microsoft.VisualStudio.TextTemplating8CBB5A87F4A34D52835396F51C533E1D8E9F22BC6977A9510B46C012D01E08C8AD263AC5BA030600D92BC0F39E7F1C3B6AA67D8CE545627E10A7F993E06C0D02.GeneratedTextTransformation.TransformText() in C:\ViewModels\BaseGridViewModels\BaseViewModels.tt:line 33 C:\ViewModels\BaseGridViewModels\BaseViewModels.tt 581