After migration Owncloud to Nextcloud problem with encryption

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Nextcloud version: 20.0.14
Operating system and version: Ubuntu 20.04
Apache version: Apache 2.4.41
PHP version: 7.3

Users cannot open certain shared Files.

Is this the first time you’ve seen this error? N

The output of your Nextcloud log
OC\Encryption\Exceptions\DecryptionFailedException: Can not decrypt this file, probably this is a shared file. Please ask the file owner to reshare the file with you.

The output of your config.php file

<?php
$CONFIG = array (
  'instanceid' => '',
  'passwordsalt' => '',
  'secret' => '',
  'trusted_domains' => 
  array (
    0 => 'sub.domain.tld',
  ),
  'datadirectory' => '/var/www/...../web/data',
  'overwrite.cli.url' => 'https://sub.domain.tld',
  'dbtype' => 'mysql',
  'version' => '20.0.14.2',
  'dbname' => 'dbname,
  'dbhost' => 'localhost',
  'dbtableprefix' => 'oc_',
  'dbuser' => 'dbuser,
  'dbpassword' => 'mypassword',
  'logtimezone' => 'UTC',
  'installed' => true,
  'loglevel' => 4,
  'mail_smtpmode' => 'smtp',
  'mail_from_address' => 'webmaster',
  'mail_domain' => 'maildomain.tld',
  'mail_smtpauthtype' => 'LOGIN',
  'mail_smtpauth' => 1,
  'mail_smtphost' => 'maildomain.tld',
  'mail_smtpport' => '25',
  'theme' => '',
  'maintenance' => false,
  'trashbin_retention_obligation' => 'auto',
  'mail_smtpname' => 'webmaster@maildomain.tld',
  'mail_smtppassword' => 'mailpassword',
  'singleuser' => false,
  'encryption.legacy_format_support' => true,
  'encryption.key_storage_migrated' => false,
  'mysql.utf8mb4' => true,
  'defaultapp' => 'files',
);

The output of your Apache/nginx/system log in /var/log/____:
there are no logentries that have to do with nextcloud in apache2 or system logs

Output errors in nextcloud.log
There is a load of notifications to tell the owner of the file to share it again.

My Questions:
can i disable “serverside encryption”?
If i do so do i need to run some occ commands to get files unencrypted?
I know we must update to version 25, must i do that first or first remove the encryption?

I would be very gratefull for any hint to get “my (next)cloud” running again after the migration from owncloud.

Regards
Jan

Read this documentation (at the end)

But i don’t know if the migration from ownCloud to Nextcloud is a problem. Think about a backup.

Thanks devnull,

could you plase check the link to “documentation” for it seems a dead link.

The migration did do function pretty well, but i guess that i also migrated the problem with a user acting as “manager” that did not handle encryption right, for some users encryption was set for others not.

That is why i would like to remove encryption alltogether.

Regards,
Jan

Here the link:

https://docs.nextcloud.com/server/latest/admin_manual/configuration_files/encryption_configuration.html

Thanks,

i had read this partly, I will now start to decrypt single users in order to see if this will work.

I think that the updates to version 25 will be done afterwards.

Regards,
Jan