Zend certified PHP/Magento developer

Why am I getting “The filename, directory name, or volume label syntax is incorrect.” in this situation on Windows 11?

On Windows 11, I am trying to do this in a .bat file:

start "nginx" cmd.exe /U /K "C:nginxnginx.exe" -c "C:UsersJohn DoeDocumentsPHP-devNginxnginx.conf" -p "C:nginx"

That means: “open a cmd.exe instance with the window title nginx, running nginx.exe with the specified arguments, and keep the window alive”.

However, it instead opens a Windows Terminal instance (with cmd.exe inside) with the text The filename, directory name, or volume label syntax is incorrect. in the top and then it exits the command instantly. Huh?

If I manually run the “actual command”, from an already opened cmd.exe or Windows Terminal, the command itself works (doesn’t exit or show any error or output):

"C:nginxnginx.exe" -c "C:UsersJohn DoeDocumentsPHP-devNginxnginx.conf" -p "C:nginx"

I was using the same command on Windows 10 without this issue (and identical directory structures), so obviously, it cannot have to do with anything in the command itself.

If instead I do:

start "nginx" "C:nginxnginx.exe" -c "C:UsersJohn DoeDocumentsPHP-devNginxnginx.conf" -p "C:nginx"

… then it does run (no error), but it does this in a Windows Terminal instance rather than cmd.exe, which breaks the taskbar grouping which I’m after!

What could it possibly be doing due to the cmd.exe /U /K (or cmd.exe /U /C) part which “invalidates” the command?

I just want it to open as a proper cmd.exe (not wrapped in Windows Terminal), just like all my other such instances which were started in the same way and by the same .bat file, and not display any weird error.