MSBuild: CSC : error CS2012: Cannot open ‘D:\UnrealEngine-4.14\Engine\Source\Programs\UnrealBuildTool\obj\Development\UnrealBuildTool.exe’ for writing – ‘The process cannot access the file ‘D:\UnrealEngine-4.14\Engine\Source\Programs\UnrealBuildTool\obj\Development\UnrealBuildTool.exe’ because it is being used by another process.’ [D:\UnrealEngine-4.14\Engine\Source\Programs\UnrealBuildTool\UnrealBuildTool.csproj]
Please check that you aren’t currently running UBT (also check Task Manager as it may have gotten stuck)
Hope that helps. Cheers,