Exited with code 999

I have a project that I started in 4.2.0. I recently came back to it, but when I try to build it in VS it immediately exits with code 999:

 Error	1	error MSB3073: The command ""C:\UE4\Unreal Engine\4.2\Engine\Build\BatchFiles\Build.bat" SpadesEditor Win64 Development "C:\Users\Kochab\Documents\Unreal Projects\Spades\Spades.uproject" -rocket" exited with code 999.	C:\Program Files (x86)\MSBuild\Microsoft.Cpp\v4.0\V120\Microsoft.MakeFile.Targets	38	5	Spades

I believe it was compiling before I quit working on it, so I’m not sure what the problem could be. I am able to build a project I started in 4.1.1 as well as 4.5.1. I tried disabling Avast as per this thread:


But I still can’t build it.

It was indeed Avast. I looked at the output window instead of the error list in VS and it said it couldn’t find UnrealBuildTool.exe. I opened up the virus chest in Avast and found UnrealBuildTool.exe for version 4.2 sitting there. I probably could have restored the file from the chest, but verifying the engine from the UE4 launcher seemed to do the trick. For anyone else with this problem, here is a short video explaining how to access the chest: