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.
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.