From aan OpenSUSE forunm thread linked in the linked answer:
Check your printer's entry in /etc/cups/printers.conf. If it has "OpPolicy" set to "authenticated" set it back to "default". Make sure you stop CUPS before editing /etc/cups/printers.conf and start CUPS afterwards. Now your printer should work again.
From aan OpenSUSE forunm thread linked in the linked answer:
Check your printer's entry in /etc/cups/ printers. conf. If it has "OpPolicy" set to "authenticated" set it back to "default". Make sure you stop CUPS before editing /etc/cups/ printers. conf and start CUPS afterwards. Now your printer should work again.