Bug: Switching between source and precompiled engine deletes UE4Editor.exe

I’ve had this issue with all recent engine versions starting from at least 4.12.

It happened to me a few times that when trying to start the editor from Visual Studio, UE4Editor.exe would be missing. At first, I thought some antimalware software or Windows Defender was deleting the file, although none reported it. I finally noticed a pattern: it happened after I had switched the game project from using the engine built from source, to a precompiled engine installed via the launcher. It only happens when you don’t delete your Intermediate folder first.

Repro steps:

  1. Have an engine built from source, a precompiled engine and a game project ready
  2. Right click the game’s .uproject > Switch Unreal Engine version > select the engine from source
  3. Open the game’s Visual Studio solution, build and run the game
  4. Close Visual Studio
  5. Right click the game’s .uproject > Switch Unreal Engine version > select the precompiled engine
  6. Open the game’s Visual Studio solution, build and run the game
  7. On two of my machines, at this point UE4Editor.exe is missing from the precompiled engine folder

This issue only happens when I don’t delete the Intermediate folder in the game project root folder. It leads me to believe that after changing engine versions, left-over Intermediate files cause Visual Studio to incorrectly delete UE4Editor.exe at the new location.

Hi ,

Thank you for reporting this issue. We had already come across this internally a few weeks ago, and it was reported in UE-38820. I have updated the ticket to include your report.