Editor crash on project load

I saved my project, restarted engine, and now i cannot open my work because its crashing engine.
I made a little research on google and this answerhub but founded nothing helpfull.

Logs: http://testy.solground.pl/Logs.7z

OS: Win7 pro
Proc: i5-3570k
Graphic: GTX 660

I can give access to my project for unreal dev stuff if needed.

Earlier today i had similar problem, but in this case there was information in log which file is causing crash, so i restored backup (it were BP of Player Controller and level file), and all work good.
Common thing for this two files is that i added switch enums, after backup restore i changed it to normal int switch.

Level map have few BP on it and point of light, no matinee, no land or whatever (primitive 2d game level).

Sorry for chaos and my english, its late here :slight_smile:

Broken uasset (PC Controller) and umap file for this problem.


BP graph which is corrupting my umap (maybe my mistake?):


I made more research and found that some problems came from struct which i attached to this post.

Corrupted struct

Hi obiekt628,

First thing I noticed was you are using a Object to set a Variable for Game Mode, Game State, and Player Controller. Is there a reason you aren’t using the pre-made Get nodes for these.

Also, I’m having trouble reproducing your issue from these files alone, it seems you are referencing a function library. Could we get a link to download the function library or the project as a whole? Feel free to Private Message me on the Forums if you’re not comfortable posting it here.

My get functions are just pre-made get nodes with cast-to node, i think i should use macros… not sure about it.

I will PM you with link to whole project, just waiting till it upload on ftp.

I’m unsure of what caused your project to become corrupted so I have submitted it to our developers to look into further. I’ll keep you posted as soon as I hear something.

Thanks, TJ

Hi obiekt628,

Thank you for reporting the issue. The problem is caused by circular dependency. The BP loading system is going to be rewritten, and in the future the issue will be fixed (details).

For now there is an unsafe fix/hack you can use to open the broken project (if you want to recompile the whole editor).
In function PreloadAndLinkIfNecessary in class FRegenerationHelper add folowwing lines:

	static void PreloadAndLinkIfNecessary(UStruct* Struct)
			auto ChangedClass = Cast<UClass>(Struct);
			UObject* OldCDO = ChangedClass ? ChangedClass->ClassDefaultObject : NULL;
			if (OldCDO)
				bool bShouldBeChanged = Struct->HasAnyFlags(RF_NeedLoad);
				for (UField* Field = Struct->Children; Field && !bShouldBeChanged; Field = Field->Next)
					bShouldBeChanged |= !Field->HasAnyFlags(RF_LoadCompleted);
				if (OldCDO && bShouldBeChanged)
					UE_LOG(LogBlueprint, Warning, TEXT("The CDO was removed during PreloadAndLinkIfNecessary: %s"), *OldCDO->GetFullName());
					ChangedClass->ClassDefaultObject = NULL;
					OldCDO->Rename(NULL, GetTransientPackage(), REN_DontCreateRedirectors | REN_ForceNoResetLoaders);
		bool bChanged = false;
		if (Struct->HasAnyFlags(RF_NeedLoad))

The only advice is to restrict circular dependency. For example in gameData the PlayerCharacter variable could be simple Pawn (afaik that would fix the issue). Sorry for inconvenience.


Hey I was having a similar issue with the editor crashing on load, but only after adding functionality to a blueprint that casts a characters anim instance to an inherited anim BP type that I created. I believe this crash happens for the same reason mentioned above, as the anim BP also references the blueprint from which this cast takes place thus a circular include ensues. I implemented this fix, and it did nothing to solve this issue unfortunately but this fix now causes the editor to crash when changing .umaps

Hi MurdoNZ,

The code above is just temporary fix/hack for very specific case. Unfortunately it’s not 100% safe and it won’t help most cyclic dependency issues.

The BP loading system is going to be rewritten (this is our top priority task), and in the future cyclic dependency issues will be fixed. Currently the best advice is to restrict cyclic dependency (Details). Sorry for inconvenience.