Upgrade V20 | Internal Server error Login

Hello Guys,
after i upgraded my NC to version 20 i can’t login in if i log myself out.
I checked the logs and i think i found the issue but i have no idea how to solve it.
System:

VPS= 8 GB RAM | 2vCPU | 400GB HDD| Debain 10 | Apache | PHP 7.4
Full error log:
Log - Pastebin.com
Section i think is the problem:
{“reqId”:“qpQMNCIAFd9d5PzZgRGC”,“level”:3,“time”:“June 14, 2021 17:02:57”,“remoteAddr”:“XXX.XXX.XXX.XXX”,“user”:"–",“app”:“index”,“method”:“POST”,“url”:"/index.php/login",“message”:{“Exception”:“Exception”,“Message”:“Argument 1 passed to OC\Core\Controller\LoginController::tryLogin() 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”:309,“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 OC\Core\Controller\LoginController::tryLogin() 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”:“tryLogin”,“class”:“OC\Core\Controller\LoginController”,“type”:"->",“args”:["*** sensitive parameters replaced ***"]},{“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”:309,“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/core/Controller/LoginController.php",“Line”:290},“CustomMessage”:"–"},“userAgent”:“Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:88.0) Gecko/20100101 Firefox/88.0”,“version”:“20.0.9.1”}

If i missed anything please let me know, so i can update this.