The error I encountered was with `start /d "c:\temp\" test.exe`, which was parsed into the arguments `/d` and `"c:\temp\" test.exe`. The path and the executable were merged into a single argument as a new path, preventing the child process from launching. In my first patch, I attempted to identify and split this combined argument, but this caused test failures in `kernelbase`. I then retested on Windows and found that Windows also parses it as `/d` and `"c:\temp\" test.exe`—Wine's parsing is consistent with Windows. However, `start` works correctly on Windows because it is a built-in command, whereas in Wine, `start` is an external executable, leading to different behavior. I will revert the changes to the parsing logic and fix the issue directly within the `start` itself. -- https://gitlab.winehq.org/wine/wine/-/merge_requests/9996#note_128507