I have successfully migrated my .NET Framework 4.8 Windows Forms application to .NET 5. Everything builds and compiles, however, when trying to open the designer view for one of my forms, I get the following error:
The call stack is as follows:
at Microsoft.VisualStudio.WinForms.RemoteClient.Loader.RemoteCodeDomDesignerLoader.EnsureDocument(IDesignerSerializationManager manager)
at Microsoft.VisualStudio.WinForms.RemoteClient.Loader.RemoteCodeDomDesignerLoader.PerformLoad(IDesignerSerializationManager manager)
at Microsoft.VisualStudio.Design.Serialization.CodeDom.VSCodeDomDesignerLoader.PerformLoad(IDesignerSerializationManager serializationManager)
--- End of stack trace from previous location where exception was thrown ---
at Microsoft.VisualStudio.Design.Serialization.CodeDom.VSCodeDomDesignerLoader.PerformLoad(IDesignerSerializationManager serializationManager)
at Microsoft.VisualStudio.Design.Serialization.CodeDom.VSCodeDomDesignerLoader.DeferredLoadHandler.Microsoft.VisualStudio.TextManager.Interop.IVsTextBufferDataEvents.OnLoadCompleted(Int32 fReload)
While I have hundreds of forms and can't 100% confirm this, this seems to be the only form with this issue. What could be causing this? Once again, no compiler issues and not a single error in the designer CS file.
Edit: I've discovered this only happens in a single project. If I create another form in this project, the same thing happens.