I think I found the culprit: I was modifying an AppArmor profile for Thunderbird. When I executed aa-logprof, I got the following message:
Enforce-mode changes: Profile: /usr/sbin/cupsd Capability: block_suspend Severity: unexpected capability rank input: CAP_BLOCK_SUSPEND If you select "Allow", you will run into the problem mentioned above. I've no idea why creating/modifying a Thunderbird profile affects the cupsd profile and why that capability is added. -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to cups in Ubuntu. https://bugs.launchpad.net/bugs/1052098 Title: AppArmor parser error for /etc/apparmor.d/usr.sbin.cupsd Status in “cups” package in Ubuntu: New Bug description: My HP printer suddenly didn't work anymore, and /var/log/syslog reported for udev-configure-printer: "failed to connect to CUPS server; giving up" I decided to reinstall cups and hplip and got the following error messages: "AppArmor parser error for /etc/apparmor.d/usr.sbin.cupsd in /etc/apparmor.d/usr.sbin.cupsd at line 18: Invalid capability block_suspend." ... and: "start: Job failed to start invoke-rc.d: initscript cups, action "start" failed." ... resulting in errors related to dpkg (dependencies problems). After commenting out the line capability block_suspend, in /etc/apparmor.d/usr.sbin.cupsd, all is well: Reinstalling cups and hplip was successful and my printer works again. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/cups/+bug/1052098/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp