Could not resolve fedAuth! Class fedAuth does not exist

Nextcloud version (eg, 20.0.5): 20.0.12.1
Operating system and version (eg, Ubuntu 20.04): Ubuntu 18.04.5 LTS
Apache or nginx version (eg, Apache 2.4.25): nginx/1.14.0
PHP version (eg, 7.4): 7.2

The issue you are facing:

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

Steps to replicate it:

  1. Login
  2. Wait some minutes
  3. Load main page
  4. HTTP Error 503

The output of your Nextcloud log in Admin > Logging:

Only old entries not related to problem

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

<?php
$CONFIG = array (
  'updatechecker' => false,
  'instanceid' => 'REMOVED',
  'passwordsalt' => 'REMOVED',
  'secret' => 'REMOVED',
  'trusted_domains' =>
  array (
    0 => 'cloud.t1ip.com',
  ),
  'datadirectory' => '/var/www/owncloud/data',
  'overwrite.cli.url' => 'REMOVED',
  'dbtype' => 'mysql',
  'version' => '20.0.12.1',
  'dbname' => 'cloud',
  'dbhost' => 'localhost',
  'dbtableprefix' => 'oc_',
  'dbuser' => 'cloud',
  'dbpassword' => 'REMOVED',
  'logtimezone' => 'UTC',
  'installed' => true,
//  'memcache.local' => '\\OC\\Memcache\\APCu',
  'memcache.local' => '\OC\Memcache\Redis',
  'memcache.distributed' => '\OC\Memcache\Redis',
  'redis' => [
     'host' => 'localhost',
     'port' => 6379,
  ],
  'memcache.locking' => '\OC\Memcache\Redis',
  'theme' => '',
  'loglevel' => 2,
  'maintenance' => false,
  'updater.secret' => REMOVED,
  'updater.release.channel' => 'stable',
  'forcessl' => true,
  "log_type" => "errorlog"
);

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

PHP message: [owncloud][no app in context][3] {"Exception":"OCP\\AppFramework\\QueryException","Message":"Could not resolve fedAuth! Class fedAuth does not exist","Code":0,"Trace":[{"file":"/var/www/owncloud/lib/private/AppFramework/Utility/SimpleContainer.php","line":126,"function":"resolve","class":"OC\\AppFramework\\Utility\\SimpleContainer","type":"->","args":["fedAuth"]},{"file":"/var/www/owncloud/lib/private/AppFramework/Utility/SimpleContainer.php","line":96,"function":"query","class":"OC\\AppFramework\\Utility\\SimpleContainer","type":"->","args":["fedAuth"]},{"function":"OC\\AppFramework\\Utility\\{closure}","class":"OC\\AppFramework\\Utility\\SimpleContainer","type":"->","args":["*** sensitive parameters replaced ***"]},{"file":"/var/www/owncloud/lib/private/AppFramework/Utility/SimpleContainer.php","line":101,"function":"array_map","args":[{"__class__":"Closure"},["*** sensitive parameter replaced ***"]]},{"file":"/var/www/o
2021/08/30 16:24:02 [error] 14064#14064: *572532 FastCGI sent in stderr: "PHP message: [owncloud][no app in context][3] {"Exception":"OCP\\AppFramework\\QueryException","Message":"Could not resolve l! Class l does not exist","Code":0,"Trace":[{"file":"/var/www/owncloud/lib/private/AppFramework/Utility/SimpleContainer.php","line":126,"function":"resolve","class":"OC\\AppFramework\\Utility\\SimpleContainer","type":"->","args":["l"]},{"file":"/var/www/owncloud/lib/private/AppFramework/Utility/SimpleContainer.php","line":96,"function":"query","class":"OC\\AppFramework\\Utility\\SimpleContainer","type":"->","args":["l"]},{"function":"OC\\AppFramework\\Utility\\{closure}","class":"OC\\AppFramework\\Utility\\SimpleContainer","type":"->","args":["*** sensitive parameters replaced ***"]},{"file":"/var/www/owncloud/lib/private/AppFramework/Utility/SimpleContainer.php","line":101,"function":"array_map","args":[{"__class__":"Closure"},[{"name":"connection","__class__":"ReflectionParameter"},{"name":"container","__class__":"ReflectionParameter"},"*** sensitive parameter replaced ***",{"name...