Internal Server Error after a failed update/rollback => cache? I had no cache!

Hello guys, I’m totally lost here. I have a ISE in Nextcloud:

Internal Server Error

The server encountered an internal error and was unable to complete your request.
Please contact the server administrator if this error reappears multiple times, please include the technical details below in your report.
More details can be found in the server log.

In /var/log/nginx/error.logI have this:

  thrown in /usr/local/www/nextcloud/lib/private/Memcache/Factory.php on line 94
" while reading response header from upstream, client: 192.168.1.46, server: _,
request: "GET //ocs/v1.php/cloud/users/albert?format=json HTTP/1.1", upstream: "
fastcgi://unix:/var/run/nextcloud-php-fpm.sock:", host: "nextcloud."
2021/10/09 11:31:05 [error] 18192#101962: *45 FastCGI sent in stderr: "PHP messa
ge: PHP Fatal error:  Uncaught OC\HintException: [0]: Memcache \OC\Memcache\Redi
s not available for distributed cache (Is the matching PHP module installed and
enabled?)

Which is weird, because I have no Memcache/Redis or anything enabled. Here’s my config:

config/      console.php
root@nextcloud:~ # cat /usr/local/www/nextcloud/config/config.php
<?php
$CONFIG = array (
  'apps_paths' =>
  array (
    0 =>
    array (
      'path' => '/usr/local/www/nextcloud/apps',
      'url' => '/apps',
      'writable' => true,
    ),
    1 =>
    array (
      'path' => '/usr/local/www/nextcloud/apps-pkg',
      'url' => '/apps-pkg',
      'writable' => true,
    ),
  ),
  'logfile' => '/var/log/nextcloud/nextcloud.log',
  'passwordsalt' => 'xxxxxx',
  'secret' => 'xxxxx',
  'trusted_domains' =>
  array (
    0 => 'localhost',
    1 => '192.168.1.5',
    2 => 'nextcloud',
    3 => 'nextcloud.',
  ),
  'datadirectory' => '/usr/local/www/nextcloud/data',
  'dbtype' => 'mysql',
  'version' => '21.0.4.1',
  'overwrite.cli.url' => 'http://localhost',
  'dbname' => 'nextcloud',
  'dbhost' => 'localhost',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'mysql.utf8mb4' => true,
  'dbuser' => 'oc_ncadmin',
  'dbpassword' => 'xxxxxx',
  'installed' => true,

Any help would be highly appreciated!