Errors after upgrade: \HeartbeatController::heartbeat()

Nextcloud version (20.0.2):
Operating system and version (Ubuntu 20.04):
Apache or nginx version (Apache 2.4.41):
PHP version (7.4.3):

The issue you are facing:
After upgrading from Nextcloud 19 to Nextcloud 20 the error log shows the following error. I do not know how to reproduce it or what the error means. It just shows up every 30min or 60min. Also I could not find anything on the internet regarding this error.

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

The output of your Nextcloud log in Admin > Logging:

{"reqId":"xxxxxxxxxx","level":3,"time":"2020-12-02T17:04:46+01:00","remoteAddr":"xxxxxx","user":"xxxxxxxx,"app":"index","method":"PUT","url":"/index.php/apps/user_status/heartbeat","message":{"Exception":"Exception","Message":"Argument 1 passed to OCA\\UserStatus\\Controller\\HeartbeatController::heartbeat() must be of the type string, null given, called in /var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php on line 169","Code":0,"Trace":[{"file":"/var/www/nextcloud/lib/private/AppFramework/App.php","line":152,"function":"dispatch","class":"OC\\AppFramework\\Http\\Dispatcher","type":"->"},
{"file":"/var/www/nextcloud/lib/private/Route/Router.php","line":308,"function":"main","class":"OC\\AppFramework\\App","type":"::"},{"file":"/var/www/nextcloud/lib/base.php","line":1008,"function":"match","class":"OC\\Route\\Router","type":"->"},{"file":"/var/www/nextcloud/index.php","line":37,"function":"handleRequest","class":"OC","type":"::"}],"File":"/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php","Line":110,"Previous":{"Exception":"TypeError","Message":"Argument 1 passed to OCA\\UserStatus\\Controller\\HeartbeatController::heartbeat() must be of the type string, null given, called in /var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php on line 169","Code":0,"Trace":[{"file":"/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php","line":169,"function":"heartbeat","class":"OCA\\UserStatus\\Controller\\HeartbeatController","type":"->"},{"file":"/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php","line":100,"function":"executeController","class":"OC\\AppFramework\\Http\\Dispatcher","type":"->"},{"file":"/var/www/nextcloud/lib/private/AppFramework/App.php","line":152,"function":"dispatch","class":"OC\\AppFramework\\Http\\Dispatcher","type":"->"},{"file":"/var/www/nextcloud/lib/private/Route/Router.php","line":308,"function":"main","class":"OC\\AppFramework\\App","type":"::"},{"file":"/var/www/nextcloud/lib/base.php","line":1008,"function":"match","class":"OC\\Route\\Router","type":"->"},{"file":"/var/www/nextcloud/index.php","line":37,"function":"handleRequest","class":"OC","type":"::"}],"File":"/var/www/nextcloud/apps/user_status/lib/Controller/HeartbeatController.php","Line":75},"CustomMessage":"--"},"userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.183 Safari/537.36 OPR/72.0.3815.320","version":"20.0.2.2"}

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


<?php
$CONFIG = array (
  'instanceid' => 'xxxxxxxxxxxxxxxx',
  'passwordsalt' => 'xxxxxxxx',
  'secret' => 'xxxxxxxx',
  'trusted_domains' =>
  array (
    0 => 'xxxxxx',
  ),
  'datadirectory' => '/var/www/nextcloud/data',
  'dbtype' => 'mysql',
  'version' => '20.0.2.2',
  'overwrite.cli.url' => 'xxxxxxxxx,
  'dbname' => 'xxxxx',
  'dbhost' => 'localhost',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'dbuser' => 'xxxxx',
  'dbpassword' => 'xxxxxxx',
  'installed' => true,
  'maintenance' => false,
  'theme' => '',
  'loglevel' => 2,
  'logfile' => '/var/log/nextcloud.log',
  'logtimezone' => 'Europe/Vienna',
  'updater.release.channel' => 'stable',
  'debug' => false,
  'defaultapp' => 'files',
  'skeletondirectory' => '',
  'memcache.local' => '\\OC\\Memcache\\APCu',
  'memcache.distributed' => '\\OC\\Memcache\\Redis',
  'memcache.locking' => '\\OC\\Memcache\\Redis',
  'redis' =>
  array (
    'host' => '/var/run/redis/redis-server.sock',
    'port' => 0,
    'timeout' => 1.5,
  ),
);