For several months now, I’ve been getting an error every time I tried to do an upgrade of my ubuntu system:

 Converting from /var/lib/cyrus/deliver.db (berkeley-nosync) to /tmp/deliver.db.cOT3kOvz (skiplist)
 fatal error: can't open old database
 dpkg: error processing cyrus-common-2.4 (--configure):
 subprocess installed post-installation script returned error exit status 75
 dpkg: dependency problems prevent configuration of cyrus-pop3d-2.4:
 cyrus-pop3d-2.4 depends on cyrus-common-2.4 (= 2.4.12-2); however:
 Package cyrus-common-2.4 is not configured yet.
 dpkg: error processing cyrus-pop3d-2.4 (--configure):
 dependency problems - leaving unconfigured
 dpkg: dependency problems prevent configuration of cyrus-pop3d:
 cyrus-pop3d depends on cyrus-pop3d-2.4; however:
 Package cyrus-pop3d-2.4 is not configured yet.
 dpkg: error processing cyrus-pop3d (--configure):
 dependency problems - leaving unconfigured
 

I tried removing cyrus altogether. But there were so many inter-dependencies that it wasn’t an option.

I finally found a clue as to how to fix it here, but I had to modify it a bit for my own situation.

I moved the deliver.db and tls_sessions.db files, then ran the upgrade command and voila! everything worked!

 sudo su -
 cd /var/lib/cyrus
 mv deliver.db deliver.db.old
 mv tls_sessions.db tls_sessions.db.old
 

Once the upgrades are done, the ‘old’ files can be removed. Yes, you might be able to get away with just deleting those files in the first place. But I like to play it safe.

Note: does this mean that there may be local mail not delivered? It could. But my local mail is only used for notifications, so it wasn’t a big deal to me.