Sorry @cgoise already explained the solution in another thread (but I am not allowed to post a link to the thread):
This seems to be related to apparmor.
sudo aa-complain /usr/bin/akonadiserver fixed it for me.
Once the issue is fixed, or if this doesn’t help in your case, you should issue a
sudo aa-enforce /usr/bin/akonadiserver ,
to reactivate apparmor.