[flyingtadpole]

More on this: I've had to re-re-reinstall Composer 4.0.2 because of other unrelated things, and having to resort to earlier backups. In the process, I notice that composer.exe, of whichever version of 3 or 4, simply fails to register at all as an application.



While the workaround is to find the .not and .notFILE in the ROOT registry key, and work down their trees to the command, and type in the location of composer.exe, nevertheless it would seem the root cause is Windows not writing Composer (any vintage) to the Registry as an application.