Editor crashes when loading my project


Today the editor started crashing when I open my project. The project is mostly (99%) blueprints.

Crashes during the startup only started today. But, yesterday the same project (and files) was compiling and running fine.

I had many others crashes before, but mostly happened after the editor was already running, so not a big problem. But with the editor crashing before it even starts I have no idea how to fix it or what is causing it.

I tried to “Verify” the engine in the Launcher, and also tried removing all the binaries files in the project’s folder and rebuild it. But these did not solve the problem.

I do have the project on version control, but to recover it I have to go back days of work, which is a big problem for me. Hope there is a fix for it…

Let me know if more info is needed. But for now I’m attaching two text files included with the crash files.

Thank you…




  • Are you able to recall the changes you made prior to the crash?
  • If so, can you reproduce the crash in a new project?

It can be quite difficult to debug a startup crash, as you’re not able to access the assets to see what sort of errors could be occurring. If the project continues to crash, you could attempt to open your older version and see if you can migrate some of the newer assets into the project, that way you can figure out exactly which assets are causing the crash.

Hey Flint,

Thank you for your attention. I have been analyzing all the commits and things are not as bad as it looks. I managed to find the exactly commit, and the exactly changes that when reverted, my editor stop launching. I made an album with the “diffs” (see link below). The changes only affect three Blueprint classes.

The weird thing is that the changes are very normal. Basically I just added a new function with the same name to three different Blueprint classes.

I’m not sure if it’s normal, but on image 2 there was some changes to a “Set” method on one of the Blueprints, but visually there is no change.

Also, image 2 shows how I deleted the method “Rebuild All” from the “BO_BaseFOR” class on this commit (I may have just renamed it to “Signal Tower Spawned”). But, that method is still present on the Log file of the crash. More specifically on this line:

[2015.11.26-19.20.55:740][  0]LogBlueprint:Error: [compiler BP_BasicTower] Error Could not find a function named "Rebuild All" in 'BO_BaseFOR_C'.
Make sure 'BO_BaseFOR_C' has been compiled for  Rebuild All 

The thing is, “BP_BasicTower” does use the “Rebuild All” method. But, the last time this BP was changed was like a week ago. So basically, somehow, after deleting the “Rebuild All” I was able to compile the project and run it multiples times without a problem, even with “BP_BasicTower” using the deleted method somehow.

So that may be the problem. “BP_BasicTower” is trying to use a method that no longer exists (but somehow worked when I removed the method, compiled and run the game without closing the Editor).

I also failed to replicate the problem on a new/fresh project.

Regardless, reverting the changes will be easy. It just took a while to find which assets were breaking the project.

Thank you for providing the information. To clarify, you are no longer experiencing an issue with your project? It seems like the issue was related to a problem that occurred when you removed a method, but now you have been able to solve that by removing the method completely?

I can replicate the problem consistently on my project, but I don’t know why. I didn’t manage to replicate it on a fresh project.

Here is a little video that might explain better:

The video shows:

  • Starting project at master branch crashes
  • Revert to an old commit, and leave only the problematic class (where I will rename the method) to the old state, then revert back everything else to the master branch
  • Renaming the method on the problematic blueprint will allow me to compile and run the game with no problems
  • Restarting will crash the editor

Not sure if related, but I have two Blueprints that always require me to compile them manually before playing the game after starting the Editor. You can see them on the video too. I tried to put their code on a fresh project and they work fine, so not sure what the problem is.

I’m right now converting those problematic Blueprints into C++ code to solve this problem, and this is fine, I have been planning to do this conversion at some point.

I believe my project will be fine with this change, so just reporting as much info as I can because if more people get this same error it will be easier to fix.

Thank you for reporting the information, and providing a video of the issue occurring. Based on what I’ve tried, I haven’t been able to get a similar issue to occur, which leads me to believe that it is something specific to an asset that you are using. If with further investigation, you are able to pinpoint the cause of the issue, please feel free to respond to this thread with repro steps so that I can reproduce the issue and investigate it further. Thank you.