Crash When Opening a Control Rig File in UE4

If by any chance that you encounter a crash when open a control rig file, this article might help you.

How I met this problem?

Actually… I do have no idea in the very beginning. Since I am doing some customization and have made lots of modification to the plugin code. Actually it worked fine and crash occurred in the next day.

And the crash is like this:


Call Stack

What is this problem?

It seems that FControlRigEitor::GetAssetEditorModeManager() function returns a nullptr? Which means there is something wrong with the editor.

Now let’s see where function SetAssetEditorModeManager is called. According to the code comments, control rig editor is much the same as Animation Blueprint Editor, so I’ll check anim bp editor source code.

I finally found call stack like this:

Anim BP Call Stack

So… Yes! This should be something wrong about persona viewport.

How to solve this problem?

Firstly, I’ll add an if... else condition to check if function GetAssetEditorModeManager() returns null to avoid crash.

Add a guard

And control rig file was opened successfully. Only with viewport closed.

Open file

Oh… I see! The problem is that I closed the viewport before exit UE4, and this result in function GetAssetEditorModeManager() returning null.

To prove this, I re-opened the viewport, and exit UE4, then revert my modification, compile, yep!!! It worked!

Final result

So the final result, is to add a guard to function GetAssetEditorModeManager() to avoid crash.

And remember to add a guard to GetEditMode() because this function would call function GetAssetEditorModeManager() without check.

Hope this article could help you…