What was in your /etc/cups/client.conf (now /etc/cups/client.conf_bak)? If it pointed to a CUPS on a remote machine, all your CUPS access (from applications/command line, not web interface) was directed to the remote machine with a different CUPS setup. Now you are using always the CUPS on your local machine.
Note that client.conf is deprecated but still working as originally intended (and so often an admin's nightmare).
What was in your /etc/cups/ client. conf (now /etc/cups/ client. conf_bak) ? If it pointed to a CUPS on a remote machine, all your CUPS access (from applications/ command line, not web interface) was directed to the remote machine with a different CUPS setup. Now you are using always the CUPS on your local machine.
Note that client.conf is deprecated but still working as originally intended (and so often an admin's nightmare).