Akonadi fails to start, `...is not operational`

Since the Stable Update 2022-02-05 Akonadi has failed to start on my system, though may not necessarily be due to the update, displaying the message “The Akonadi personal information management service is not operational” when I try to use KOrganizer or KJots.

On a previous instance of this problem (2017 may be!) I replaced the directories:


with their recent backup and Akonadi worked fine again, but is there a better way to try and restore Akonadi?

I am aware there is akonadictl but I have never used it and I am reluctant to do so until I learn more as, of course, I do not want to lose any settings or personal information.

Since my first post to I have tried a few things restore Akonadi and my data. Before each I would ensure Akonadi was stopped, akonadictl stop:

The first was from @ishaanbhimwal’s reply to remove ~/local/share/akonadi, by renaming it to akonadi2022Feb11. That was only partially successful as Akonadi would start but only one calendar was visible in KOrganizer and only birthdays and no one-off events that I had entered (see later) and, I believe, nothing appeared in Kjots.

Next I did as I described above replacing ~/.config/akonadi and ~/.local/share/akonadi with their backups. Perhaps not surprisingly Akonadi became not operational again.

So I then tried removing everything Akonadi, KOrganizer, KJots, KNotes and Korgac related from ~/.cache, ~/.config and ~/.local and replacing them with backups. That helped as all the calendars were present. However all the RAM and swap got fully used up and new .ics calendar files were being created every few seconds in ~/.local/share/akonadi_ical_resource_0 and akonadi_ical_resource_1, resulting in thousands of files. korgac was the culprit so I ended that process but later mysqld was a similar problem.

Next and to date I removed ~/.local/share/akonadi, ~/.local/share/akonadi_ical_resource_0 and ~/.local/share/akonadi_ical_resource_1 and restarted Akonadi, akonadictl start. So far things seems back to normal except…

I have lost all one-off events in my calendar since February 2020, only repeating events remain! I would expect to find those events somewhere in my backups but found none so far - suggestions of where to look are welcome.