My issue has popped up recently. I am unsure of what might be going wrong, but this error is making Unreal not have all the functionality it had previously (namely running without errors).
I have already done quite a bit of research, and found nothing specific to fix. Everything appears to be up to date and running fine. I had a few minor issues that I found in the meantime, but nothing I fixed changed how Unreal functioned.
Please Help. Here is what I have for available info, let me know if you need more.
Just to let you know, it was AVG… It was blocking all executable files associated with Unreal due to the newest AVG update.
Since this has been answered (by me), I should put the info in here. If you have AVG, and notice that this issue has come up for you, the solution is to add exceptions for the UnrealBuildTool.exe (and most likely for Lightmass and Swarm also).