Error when packaging after switching to 4.21

Hi everyone,
We are a small game developer studio that is currently working on our first project, and we have encountered a serious problem with the latest version of Unreal Engine.

Our project was originally made in version 4.19, where the game worked perfectly both by running it with the editor and when packaging it into an exe. However, we are now forced to use the latest version 4.21.2 to create a build that works for PS4.

We have migrated the project to the new version, and inside Unreal everything works correctly except for a few errors found in tools that have been updated since 4.19, problems that we managed to solve without further issues.
However, when trying to create a package from the 4.21 version the following error occurs over and over:

UATHelper: Packaging (Windows (64 bit)): LogWindows: Error [Callstack]: 0x0007ffde5e9382b UE4Editor - UWG.d11 !Unkown Function[]

We have tried endless solutions and have looked for info everywhere, but we have been stuck with this problem for 2 weeks.

We have cleaned the project by removing unnecessary files and have tried to make partial builds with only a few elements, but whenever there are blueprints involved the error strikes again.

Thanks in advance

.

Stack overflow usually happens when you get in an infinite loop.

Install the Debugging Symbols for the engine, and you’ll receive a more explanatory stack trace, with which you’ll hopefully be able to track down the culprit call.

Thanks! We installed Debugging Symbols and tracked down the conflict to this message, but we still don´t know how to solve it.

[link text][2]

Well you can see that it gets in an endless loop in ShouldSerializeWidgetTree. The only place ShouldSerializeWidgetTree calls itself is in UserWidget’s line 1858, when it iterates through objects.

Based on this, I think there might be a cross-reference problem. You can try setting a breakpoint to this call, let some iteration to be done, and check in the stack trace which objects are being circled. That might lead you to the right direction.

Thank you very much for your help. Following your indications we managed to isolate the widget cross-reference problem, and managed to package and build our project succesfully after removing the conflicting issues.