How to fix CompilerResultsLog: ERROR: A conflicting instance of UnrealBuildTool is already running

When I pressed build in visual studio, this error message came up and I don’t know how to fix it.


I fixed the error by changing the solution configuration in visual studio from development editor to development.

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Restart PC, Mac Laptop.


Find and kill dotnet.exe in your task manager process details list.


For me this seems to be some kind of concurrency issue with the UE build system from the editor. For me it happens randomly when packaging a plugin. Just re-running the command a second or third time does the trick. This still happens in UE 5.4.1 and has since at least UE 5.2.1