Hello !
I use Nextcloud to share files between a Raspberry with an external HDD and two computers at home. I don’t know much about linux administration, apache or databases so forgive my mistakes in advance …
For several months now, a folder has been locked in our nextcloud and we can not do anything about it, modify it or delete it. This generates many errors in the logs (see after), but having already spent a lot of time on them without finding solutions, I gave up …
But now a second file is completely blocked. This one is very important. I saved it on my computer (phew!) But I would find it stupid to just change the name of my file without looking for the problem! 
But here, like the last time, I can’t find any solution that works. The last one found is this one which corresponds a lot to my problem:
https://help.nextcloud.com/t/file-is-locked-how-to-unlock/1883
But I am unable to modify the database, and the installation of Redis doesn’t seems working properly ( log : Memcache \OC\Memcache\Redis not available for local cache)
Can you help me ?
Thanks a lot !
Nextcloud version (eg, 12.0.2): 12.0.3
Operating system and version (eg, Ubuntu 17.04): Osmc 4.14.34-2
Apache or nginx version (eg, Apache 2.4.25): 2.4.25
PHP version (eg, 7.1): PHP 7.0.27-0+deb9u1
The output of the error in Nextcloud log in Admin > Logging:
Fatal webdav OCA\DAV\Connector\Sabre\Exception\FileLocked: "FicXXXXXX/FraXXXXXX.xls" is locked
/var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Tree.php - line 179: OCA\DAV\Connector\Sabre\File->delete()
/var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/CorePlugin.php - line 287: Sabre\DAV\Tree->delete('files/userXXXXXX/Fi...')
[internal function] Sabre\DAV\CorePlugin->httpDelete(Object(Sabre\HTTP\Request), Object(Sabre\HTTP\Response))
/var/www/nextcloud/3rdparty/sabre/event/lib/EventEmitterTrait.php - line 105: call_user_func_array(Array, Array)
/var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php - line 479: Sabre\Event\EventEmitter->emit('method DELETE', Array)
/var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php - line 254: Sabre\DAV\Server->invokeMethod(Object(Sabre\HTTP\Request), Object(Sabre\HTTP\Response))
/var/www/nextcloud/apps/dav/lib/Server.php - line 258: Sabre\DAV\Server->exec()
/var/www/nextcloud/apps/dav/appinfo/v2/remote.php - line 33: OCA\DAV\Server->exec()
/var/www/nextcloud/remote.php - line 162: require_once('/var/www/nextcl...')
{main}
The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):
<?php
$CONFIG = array (
'instanceid' => 'xxxxxxxxxxxxxx',
'passwordsalt' => 'xxxxxxxxxxxxxxxxxxxxxxxxxxxx',
'secret' => 'xxxxxxxxxxxxxxxxxxxxxxxxxxxx',
'trusted_domains' =>
array (
0 => 'x.x.x.x',
1 => 'xxxxxxxxxxxxxx',
),
'datadirectory' => '/media/xxxxxx/data-nextcloud/',
'overwrite.cli.url' => 'https://xxxxxxxxx/nextcloud',
'dbtype' => 'mysql',
'version' => '12.0.3.3',
'dbname' => 'nextcloud',
'dbhost' => 'localhost',
'dbport' => '',
'dbtableprefix' => 'oc_',
'dbuser' => 'oc_userxxxxx',
'dbpassword' => 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx',
'logtimezone' => 'UTC',
'installed' => true,
'log_type' => 'owncloud',
'logfile' => 'nextcloud.log',
'loglevel' => '3',
'logdateformat' => 'F d, Y H:i:s',
'maintenance' => false,
'theme' => '',
'trashbin_retention_obligation' => '3, 5',
'updater.secret' => 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx',
);
The output of your Apache/nginx/system log in /var/log/____:
(I can’t access to the /var/log/apache2, permission denied… I just discovered it… Another problem, cool… ><)