Update crashes, starts new install. Help

This is not the first time I have had problems when updating from the web interface. I would say that 3/4 updates end in severe crashes, some of these end in clean installs. (Most likely my lack of knowledge)

This time is dose not show maintenance mode, I have been able to rectify that problem.
This time it shows that there is no nextcloud installed at all when i go to the web ui.

What do I do? do I reinstall the backup? Do I need to do all updates via the terminal from now on, is that more stable?

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Nextcloud version 21
Running on Unraid

Crashes under update.

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

Steps to replicate it:

  1. Update from web ui, all errors where sorted.
  2. Unable to backup
  3. Stop update
  4. Craches
  5. Try to upgrade via terminal
  6. Nextcloud is now gone"web ui" not the data.
  7. Shows new install

nextcloud

The output of your Nextcloud log in Admin > Logging:

PASTE HERE
<?php $CONFIG = array ( 'memcache.local' => '\\OC\\Memcache\\APCu', 'datadirectory' => '/data', 'instanceid' => 'x', 'passwordsalt' => 'x', 'secret' => 'x', 'trusted_domains' => array ( 0 => 'x', 1 => 'x', ), 'dbtype' => 'mysql', 'version' => '21.0.2.1', 'overwrite.cli.url' => 'https:x', 'dbname' => 'nextcloud', 'dbhost' => 'x', 'dbport' => '', 'dbtableprefix' => 'oc_', 'mysql.utf8mb4' => true, 'dbuser' => 'nextcloud', 'dbpassword' => 'x', 'installed' => true, 'default_phone_region' => 'NO', 'maintenance' => false, 'updater.secret' => 'x', );