So an additional
'single quote character in core.conf and missing double quotes around salt and password hash in web.conf.
And I found another issue that the first service start of the web UI fails, which is resolved automatically once the main service daemon is stopped once: https://github.com/MichaIng/DietPi/comm ... da75a1d89e
I wonder why I didn't run into those issues on earlier tests, probably because on Stretch and Buster the service still start up fine, while the config files are simply ignored (hence login via global software password does not work).
I'll try to send a live patch as well.