Compiling corrupts Unreal

When i compile my game, sometimes(while editor is still open, but not playing) something happens and Unreal itself gets corrupted. After i can’t run the engine nor compile my project.

It happened to me 4 times by now and since it doesn’t happen everytime, i couldn’t figure out why it happens. But one thing for sure, it always happens when i compile and the engine is running. I am trying to figure out what is the core of the problem. But it is a hard to reproduce error as it happens randomly and everytime i have to verify the engine(meaning 1.5 gb download).

If i can get more info i will post them here. Hope this will get fixed soon

Note: I am very sure Unreal is not selected to be compiled.

How does it corrupt?

No idea, i try to compile my project. Rarely something else happens and it says it can’t find some of the engine headers and such. After that i realize somehow engine got corrupted.

I am really trying to find why such thing happens. But it is inconsistent and therefore i can’t understand what really causes it. Happened 4 times since i started using 4.9

Hello Corpse0327,

I have a few questions for you about this issue,

  1. When you mention that the editor gets corrupted, do you mean that the editor crashes? Does it freeze and not do anything? Does the crash reporter window appear when this occurs?
  2. If the editor is crashing, can you post the callstack? This is located in the crash reporter window.
  3. Does this happen for any projects, such as a fresh blank project or only in your particular project?
  4. Are you using a version of the engine that you downloaded from the Epic Games Launcher or a source code version from GitHub?
  5. Does this also occur if the engine is closed when you compile your game? It could be an issue relating to hot reloading which only occurs if the editor is open at the time of compilation.


  1. Editor doesn’t crash, but you can never open it again. Have to verify it from launcher so it fixes whatever files got corrupted.

  2. It only happens in my particular project, however i don’t think i am able to really test if it happens in every project. Because it rarely happens. The problem is inconsistent.

  3. The editor provided by Epic Games Launcher. Not one i compiled.

  4. It happens randomly. I couldn’t find a particular reason which would cause this.

Lastly, i think i got rid of the problem. Problem never occurred after i remove FORCEINLINE macros from a class of my own.

Here is an example of before and after:

FORCEINLINE bool IsVerticalMove(int32 MoveCount) const; // before
bool IsVerticalMove(int32 MoveCount) const; // after

However i am not sure if problem is no more present, it is just that i assume it is because i have not experienced it since then.

I will keep this open for a little while, and if no problem arises i will just close this.

I am closing this, as i have not experienced this again and wasn’t able to really find the cause of the problem. Most probably something related to project. However corrupting UE Editor was unexpected.

Hope no one ever experiences this.