Hello, i’m starting to work on the AI implementation of my game. I created a new blueprint based of the AI Controller called EnemyController. I set the AI controller class of the enemy blueprint to EnemyController, i compile fine and save everything and close the editor. When i execute the editor again, it always crashes on the line check(PreviousCDO != nullptr); in the method RegenerateBlueprint of BlueprintEditorUtils.cpp. I have to revert the enemy blueprint from git to be able to launch the editor again, but if i do that i’m back to square one. I wasn’t able to replicate this issue on a fresh project, so can what is the reason for this error and how can i fix it so i can launch the editor again. Thank you.
Hi xlar8or,
Would you be able to provide a little more information about this issue?
- What version of the Engine are you using?
- Are you using the binary version installed by the Launcher, or did you build the Engine from source code?
- Did you customize the AIController class, or did you derive from the standard AIController class?
- Could you provide the full callstack provided by the crash?
I’m using the latest version from the release branch on git (4.6.1). The Enemy Controller simply derives from AIController and doesn’t declare nothing new. Ever since i changed my UMG widgets, the crash hasn’t happened, but i’m constantly having corrupted UMG blueprints which doesn’t allow me to start the editor and i have to revert everything through git. It’s really annoying because i have to redo the same things over and over again until somehow it doesn’t crash, which takes a lot of my time and patience. I created a question regarding one of the issues i encountered here, that may be one of the culprints in some way. Since the issue from this question is not happening (yet) i think we can close it, although the problem is still there somewhere, but now that is not crashing it will be much harder to figure out the explicit reason.
I will go ahead and mark this issue as resolved for now, since this issue appears to have stopped occurring. If you start seeing it again, please let us know.
PS. Tomorrow I will see if I can direct some attention towards the UMG question that you linked.
Thank you very much 
I think Blueprints/UMG definitely needs some attention, because if they corrupt you can’t start the editor without removing the corrupted file, not to mention the time that is going to waste if you didn’t backup those files. Unfortunately these problems are hard to reproduce and sometimes appear to be random. From my experience this crash happens always in the regeneration of the blueprint and i believe every time i had a blueprint corrupted it always crashed in that line of code. The other issue that i linked is still happening.