Printing with cups not possible any more after system upgrade in Debian

[git2fa]

Please refer to this bug description at Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1053511

Today I purged all packages of cups in Debian 11 and deleted the contents in the directory /etc/cups and /var/cache/cups.
Then I installed the packages again. Cups can be reached under http://localhost:631/admin/ and no printer is configured now.
But when I click on "Add printer" the message is "Gesamte Anfrage zu groß" -> "complete request to big" again.
There is no file in /var/log/cups and no additional error message.

What must be done to get cups working again?

[git2fa]

Installed packages in Debian 11 are now:

ii  cups                                              2.3.3op2-3+deb11u6                         amd64        Common UNIX Printing System(tm) - PPD/driver support, web interface
ii  cups-browsed                                      1.28.7-1+deb11u2                           amd64        OpenPrinting CUPS Filters - cups-browsed
ii  cups-client                                       2.3.3op2-3+deb11u6                         amd64        Common UNIX Printing System(tm) - client programs (SysV)
ii  cups-common                                       2.3.3op2-3+deb11u6                         all          Common UNIX Printing System(tm) - common files
ii  cups-core-drivers                                 2.3.3op2-3+deb11u6                         amd64        Common UNIX Printing System(tm) - driverless printing
ii  cups-daemon                                       2.3.3op2-3+deb11u6                         amd64        Common UNIX Printing System(tm) - daemon
ii  cups-ppdc                                         2.3.3op2-3+deb11u6                         amd64        Common UNIX Printing System(tm) - PPD manipulation utilities
ii  cups-server-common                                2.3.3op2-3+deb11u6                         all          Common UNIX Printing System(tm) - server common files
ii  libcups2:amd64                                    2.3.3op2-3+deb11u6                         amd64        Common UNIX Printing System(tm) - Core library
ii  libcups2:i386                                     2.3.3op2-3+deb11u6                         i386         Common UNIX Printing System(tm) - Core library
ii  mfc9332cdwcupswrapper:i386                        1.1.4-0                                    i386         Brother CUPS Laser Printer Definitions

[jschwender]

enable debugging
https://wiki.debian.org/CUPSDebugging#The_CUPS_Error_Log
try another browser

[git2fa]

Thanks for the answer and your tip!

But it only shows that there seems to be a deeper problem.
Calling as root, because a normal user has no access to cupsctl:

# cupsctl --debug-logging
cupsctl: Gesamte Anfrage zu groß

And it is not dependent on the browser, because Opera shows the same result:

There is still no logfile after this errors.
Cups seems to be resistant to any debugging of this Error.

[git2fa]

Problem found for myself now.

The reason is a misconfiguration in apparmor, that prevents cups from changing of some directories like the log directory.
After disabling apparmor for cupsd everything is working again.
The details can be found in the Debian bug report.
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1053511