Sudden constant disconnects/maintenance mode and high CPU usage


My windows client (windows-10.0.19045) recently started experiencing weird disconnects. The only way to connect again is to kill/restart the client.

When i looked into it I noticed that the webpage frequently (10-30 times an hour) states “Maintenance Mode”, and then after a few seconds or minutes displays the file list after refreshing the page a few times.

These brief switches to maintenance mode coincide with the windows client permanently loosing its connection.

When investigating further, I noticed that the CPU load was constantly high (50-90%) which is weird because it has been running on 1-20% mostly for the last few years.
Giving the VM (qemu/proxmox) two more cores and doubling the RAM (4 → 8GB) mitigated the CPU load linearly, but did not stop the constant maintenance modes/disconnects.

I am only one user with four devices accessing the server, this has not changed for the past 2-3 years.
My server is 25.0.6, running as a snap on Ubuntu 22.04.2 LTS (fully updated, both Snap and packages).

The logs in nextcoud present the followin two errors frequently:

  1. " OCA\Circles\Exceptions\MigrationException: A migration process is already running"

  2. “Doctrine\DBAL\Exception\UniqueConstraintViolationException: An exception occurred while executing a query: SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry ‘625-bookmark-1’ for key ‘oc_bookmarks_tree.PRIMARY’”

I’m scratching my head and do not even know where to start looking for a source to this… Any help or guidance would be greatly appreciated.

I think I finally solved it.
First I set the logging policy to “warning” instead of the default setting “debug”, which actually lowered the load from above 1 to 0.90-0.99.

The second error message stated that there was no app involved, but when I read it more carefully I saw that it repeatedly mentions “bookmark” in the body of the message.
I disabled the “bookmarks” app and the error dissappeared, and now the server runs smoothly/stably again.

I liked the bookmarks app, but I guess I’ll have to look for an alternative.