[Issue] Changes to system PATH environment variable breaks UE4

I had recently made some manual changes to my system’s PATH environment variable on a dev machine while configuring some fresh installs and after these changes UE4 was unable to build, debug, or even generate project files.

The process would just hang indefinitely when attempting any of these.

After manually changing the PATH variable back to it’s previous value, everything works fine again.

Is this a known issue and if so, is there a workaround to stop this behaviour?


The system is running Windows 7 64-bit, AMD architecture

The PATH changes included adding the path variable for CMake and the path variable for MySQL server 5.6

Is UE4 storing the system PATH variable somewhere and relying on it to not change or something? Would love to find a solution for this because I really hate having to set up these variables in scripts manually whenever I need to use CMake lol

My PATH don’t even mention unreal or visual studio and i changed it (using system settings) in the past with UE4 installed and there was no issues. How do exacly changing that PATH?

Yeah UE4 doesn’t add itself to the system PATH, as it has no need to. For visual studio it probably depends on what versions and tools you have installed.

The CMake path had to be set manually because of an issue with CMake’s installer and an issue with how it handles PATH lengths on windows. It’s a common and well documented issue on windows systems. Adding it is exactly how you would expect (i.e. adding the path to CMake’s bin folder). I have no idea how or why this effected UE4 (seems like it was specifically effecting the UBT) but it most certainly was the cause.

Anyone from the Epic team know anything about this? I resolved it by reverting the path but it’s gonna be a real pain in the butt to have to manually script the CMake path whenever I need to generate projects with cmake.

Hey 9KGameStudio-

What changes are you making to your path? When you try to build/debug/GenerateProjectFiles is there any message when it fails to complete after changing the path?



Hey, sorry I forgot about this thread.

The changes to my system path variable was just adding the required path variables for both cmake and for MySQL5.6. They were just the standard paths used by those applications. I did however add them manually rather than with any sort of system tool but that wouldn’t matter since the paths were configured correctly.

As for the error, I should have logged it but it was very generic and just simply said it failed to generate the project files but gave no reasons or causes.

As soon as I removed the path variables, everything was back to normal.