I ran into something similar after updating to SP21. It’s not really documented well, but the runtime isolation became stricter. First test something very simple like: pszApplicationName := 'C:\Windows\System32\notepad.exe'; pszCommandLine := ''; If that fails, it's definitely security context. Alternative architecture In some projects we moved the external executable into: PlcLogic\ and executed it from there only. Geometry Dash Lite