Update error from V18.0.3 to v18.0.6

I have my own manual backup.

There is also a backup integrated within the update process. I can’t understand why this does not revert to the V18.0.3.

What should I do?

Nextcloud version (eg, 18.0.3): 18.0.3
Operating system and version : Debian
Apache or nginx version (eg, Apache 2.4.25): Apache
PHP version : 7.3

The issue you are facing:

Unsuccessful update.

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

Steps to replicate it:

The output of your Nextcloud log in Admin > Logging:

Preparing update

Set log level to debug

Turned on maintenance mode

Repair step: Repair MySQL collation

Repair info: Not a mysql database -> nothing to do

Repair step: Repair SQLite autoincrement

Doctrine\DBAL\Exception\NotNullConstraintViolationException: An exception occurred while executing 'INSERT INTO oc_file_locks (id, lock, "key", ttl) SELECT id, lock, "key", ttl FROM __temp__oc_file_locks': SQLSTATE[23000]: Integrity constraint violation: 19 NOT NULL constraint failed: oc_file_locks.key

The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):

$CONFIG = array (
  'instanceid' => 'XXXXX',
  'passwordsalt' => 'XXXX',
  'secret' => 'XXXXX',
  'trusted_domains' => 
  array (
    0 => 'XXXXX',
  'datadirectory' => 'XXXXX',
  'dbtype' => 'sqlite3',
  'version' => '',
  'overwrite.cli.url' => 'https://XXXXXX',
  'dbname' => 'XXXXXX',
  'dbhost' => 'localhost',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'installed' => true,
  'maintenance' => false,
  'theme' => '',
  'loglevel' => 2,
  'updater.secret' => XXXX

The output of your Apache/nginx/system log in /var/log/____: