I recently upgrade from kubuntu 20.04->21.04->21.10

Once at 21.10 everything seem to work fine (yesterday) but today a massive lot of updates were installed (not unexpected) however during these updates kmail stopped working.

Once I got around to restarting kmail (it wouldn't restart) I discovered akonadi had crashed and would not start again. Much digging around later it seems it is because mysql will not start and much digging around later it looks like the data in db_data is corrupt. Specifically there is something wrong with ib_logfile0 and it seems to expect ib_logfile1 to be present but it isn't.

So at this point I made a copy of this directory and trying loads of different stuff (found on the internet) nothing has fixed it. Deleting ib_logfile0 allows akonadi to start and I have my IMAP accounts but several years worth of mail in my local mail directories has been lost.

I have no idea what has gone wrong. kmail crashed because akonadi crashed. Akonadi crashed during a big bunch of updates after upgrading from 21.04 to 21.10. Prior to the crash it appeared to be running fine on kubuntu 21.10.

I do not know where to start with recovery of my mail or where the bug belongs or what the bug is only that akonadi borked during updates and it appears I've lost emails as a result.

Obvs not easy to sort out but kmail/akonadi should be robust enough to facilitate easy recovery in this case.

kmail 5.18.1