Unable to initialize a sync journal

There is a problem with one of my colleague who use the nextcloud desktop app o windows 7 (v2.3.2) with nextcloud server 10.0.4 : when he synchronized a third client on his account, his first synchronized account stops synchronizing with an error : “Impossible d’initialiser un journal de synchronisation” wich is translated by “Unable to initialize a sync journal”.

I found anything about this error that can be related to his problem. I tried some things :

  • When I delete the account and start again synchronizing, it works again, but for a few times (some hours).
  • When the third sync is deactivated, its works again (he needs it).
  • I found a file ._sync_a527a11d3060.db-shm was synchronized on the server around the time the first problem appear. I delete it, thinking it could created some sync conflits, but didn’t resolve my problem.

Nothing strange appear in .owncloudsync.log.
Last time I tried something, he sends me another screenshot of hidden files in his sync file :
Capture (1)
which I find a bit strange, according to the red crossed db-shm file, but can’t explain it.

Is there someone had an idea about this problem ?

Many thanks.