File can not be synced with client

Nextcloud version : 24.01 snap install
Operating system and version : 20.04
Apache or nginx version (eg, Apache 2.4.25): apache
PHP version (eg, 7.4): replace me

The issue you are facing:
One of my users can not download some files. Not via browser. Not via desktop-client.
Error message says:
OC\Encryption\Exceptions\DecryptionFailedException: Cannot decrypt this file, probably this is a shared file. Please ask the file owner to reshare the file with you.
In the browser you can look at it, but no download or copy to different directory is possible.
Encryption is not active.

Is this the first time you’ve seen this error? (Y/N): Y

Steps to replicate it:

  1. start sync with client
  2. see errormessage

Did you check the file permissions on the server?
Did the file owner re-share the file(s)?

it is not a shared file - so I think it should be fine.

What about my first question?

maybe i dont understand you exactly.
do you mean the permissons in nextcloud for that user? The file belongs to the user so that should not be an issue i guess.
or do you mean the permission for the webserver? It is a snap installation, so i didnt feel the need to change sth there. Other files in the same directory sync fine.

it actually might have been encryption :face_with_open_eyes_and_hand_over_mouth:
i can not recall turning that on and off - but it is not enabeled at the moment … :thinking:
have found this in the files that are not syncing:
HBEGIN:oc_encryption_module:OC_DEFAULT_MODULE:cipher:AES-256-CTR:signed:true:HEND

what do i need to get this files decrypted again
i tried on a backup
occ encryption:enabled
occ encryption:decrypt-all
that didnt do the trick… is ther a different way?