Argument 1 passed to OC\Core\Controller

Ever since i did the dist upgrade to buster on my rpi 2, i get an error message every 5 minutes from my nc18.0.3 and have no idea what could cause it:
Error
index
vor 3 Minuten
Exception: 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 170
/var/www/nextcloud/lib/private/AppFramework/App.php - line 125:

OC\AppFramework\Http\Dispatcher->dispatch(OC\Core\Cont … {}, “tryLogin”)

/var/www/nextcloud/lib/private/AppFramework/Routing/RouteActionHandler.php - line 47:

OC\AppFramework\App::main(“OC\Core\C … r”, “tryLogin”, OC\AppFramew … {}, { _route: "c … "})

<>

OC\AppFramework\Routing\RouteActionHandler->__invoke({ _route: "c … "})

/var/www/nextcloud/lib/private/Route/Router.php - line 299:

call_user_func(OC\AppFramew … {}, { _route: "c … "})

/var/www/nextcloud/lib/base.php - line 1008:

OC\Route\Router->match("/login")

/var/www/nextcloud/index.php - line 38:

OC::handleRequest()

Verursacht durchTypeError: 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 170
/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php - line 170:

OC\Core\Controller\LoginController->tryLogin("*** sensiti … *")

/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php - line 99:

OC\AppFramework\Http\Dispatcher->executeController(OC\Core\Cont … {}, “tryLogin”)

/var/www/nextcloud/lib/private/AppFramework/App.php - line 125:

OC\AppFramework\Http\Dispatcher->dispatch(OC\Core\Cont … {}, “tryLogin”)

/var/www/nextcloud/lib/private/AppFramework/Routing/RouteActionHandler.php - line 47:

OC\AppFramework\App::main(“OC\Core\C … r”, “tryLogin”, OC\AppFramew … {}, { _route: "c … "})

<>

OC\AppFramework\Routing\RouteActionHandler->__invoke({ _route: "c … "})

/var/www/nextcloud/lib/private/Route/Router.php - line 299:

call_user_func(OC\AppFramew … {}, { _route: "c … "})

/var/www/nextcloud/lib/base.php - line 1008:

OC\Route\Router->match("/login")

/var/www/nextcloud/index.php - line 38:

OC::handleRequest()

Problem has fixed itself as it seems, probably with some app or nc update…