Wie weißen Screen nach Login debuggen?

Hallo, 

ich gehe gerade das folgende Tutorial durch: Shopware 6: Step 5: Adding associations to the entity

Nach dem ich die Migration eingespielt habe und die Entities (bundle, bundle_translation und bundle_product) registriert habe bekomme ich einen weißen Bildschirm im Backend nach dem Login,

Errrorlog nach dem Login bekommt folgende Einträge: 

[2020-12-30 15:48:10] php.INFO: User Deprecated: The "Symfony\Component\Debug\DebugClassLoader" class is deprecated since Symfony 4.4, use "Symfony\Component\ErrorHandler\DebugClassLoader" instead. {"exception":"[object] (ErrorException(code: 0): User Deprecated: The \"Symfony\\Component\\Debug\\DebugClassLoader\" class is deprecated since Symfony 4.4, use \"Symfony\\Component\\ErrorHandler\\DebugClassLoader\" instead. at /var/www/html/vendor/symfony/debug/DebugClassLoader.php:16)"} []
[2020-12-30 15:48:10] request.INFO: Matched route "api.oauth.token". {"route":"api.oauth.token","route_parameters":{"_route":"api.oauth.token","auth_required":false,"_controller":"Shopware\\Core\\Framework\\Api\\Controller\\AuthController::token"},"request_uri":"http://localhost/api/oauth/token","method":"POST"} []
[2020-12-30 15:48:12] php.INFO: User Deprecated: The "Symfony\Component\Debug\DebugClassLoader" class is deprecated since Symfony 4.4, use "Symfony\Component\ErrorHandler\DebugClassLoader" instead. {"exception":"[object] (ErrorException(code: 0): User Deprecated: The \"Symfony\\Component\\Debug\\DebugClassLoader\" class is deprecated since Symfony 4.4, use \"Symfony\\Component\\ErrorHandler\\DebugClassLoader\" instead. at /var/www/html/vendor/symfony/debug/DebugClassLoader.php:16)"} []
[2020-12-30 15:48:12] request.INFO: Matched route "administration.index". {"route":"administration.index","route_parameters":{"_route":"administration.index","auth_required":false,"_controller":"Shopware\\Administration\\Controller\\AdministrationController::index"},"request_uri":"http://localhost/admin","method":"GET"} []
[2020-12-30 15:48:13] php.INFO: User Deprecated: The "Symfony\Component\Debug\DebugClassLoader" class is deprecated since Symfony 4.4, use "Symfony\Component\ErrorHandler\DebugClassLoader" instead. {"exception":"[object] (ErrorException(code: 0): User Deprecated: The \"Symfony\\Component\\Debug\\DebugClassLoader\" class is deprecated since Symfony 4.4, use \"Symfony\\Component\\ErrorHandler\\DebugClassLoader\" instead. at /var/www/html/vendor/symfony/debug/DebugClassLoader.php:16)"} []
[2020-12-30 15:48:13] php.INFO: User Deprecated: The "Symfony\Component\Debug\DebugClassLoader" class is deprecated since Symfony 4.4, use "Symfony\Component\ErrorHandler\DebugClassLoader" instead. {"exception":"[object] (ErrorException(code: 0): User Deprecated: The \"Symfony\\Component\\Debug\\DebugClassLoader\" class is deprecated since Symfony 4.4, use \"Symfony\\Component\\ErrorHandler\\DebugClassLoader\" instead. at /var/www/html/vendor/symfony/debug/DebugClassLoader.php:16)"} []
[2020-12-30 15:48:13] php.INFO: User Deprecated: The "Symfony\Component\Debug\DebugClassLoader" class is deprecated since Symfony 4.4, use "Symfony\Component\ErrorHandler\DebugClassLoader" instead. {"exception":"[object] (ErrorException(code: 0): User Deprecated: The \"Symfony\\Component\\Debug\\DebugClassLoader\" class is deprecated since Symfony 4.4, use \"Symfony\\Component\\ErrorHandler\\DebugClassLoader\" instead. at /var/www/html/vendor/symfony/debug/DebugClassLoader.php:16)"} []
[2020-12-30 15:48:13] php.INFO: User Deprecated: The "Symfony\Component\Debug\DebugClassLoader" class is deprecated since Symfony 4.4, use "Symfony\Component\ErrorHandler\DebugClassLoader" instead. {"exception":"[object] (ErrorException(code: 0): User Deprecated: The \"Symfony\\Component\\Debug\\DebugClassLoader\" class is deprecated since Symfony 4.4, use \"Symfony\\Component\\ErrorHandler\\DebugClassLoader\" instead. at /var/www/html/vendor/symfony/debug/DebugClassLoader.php:16)"} []
[2020-12-30 15:48:13] request.INFO: Matched route "api.info.entity-schema". {"route":"api.info.entity-schema","route_parameters":{"_route":"api.info.entity-schema","_controller":"Shopware\\Core\\Framework\\Api\\Controller\\InfoController::entitySchema","version":"2"},"request_uri":"http://localhost/api/v2/_info/entity-schema.json","method":"GET"} []
[2020-12-30 15:48:13] request.INFO: Matched route "api.admin.snippets". {"route":"api.admin.snippets","route_parameters":{"_route":"api.admin.snippets","_controller":"Shopware\\Administration\\Controller\\AdministrationController::snippets","version":"2"},"request_uri":"http://localhost/api/v2/_admin/snippets?locale=en-GB","method":"GET"} []
[2020-12-30 15:48:13] request.INFO: Matched route "api.info.me". {"route":"api.info.me","route_parameters":{"_route":"api.info.me","_controller":"Shopware\\Core\\Framework\\Api\\Controller\\UserController::me","version":"2"},"request_uri":"http://localhost/api/v2/_info/me","method":"GET"} []
[2020-12-30 15:48:13] request.INFO: Matched route "api.info.open-api-schema". {"route":"api.info.open-api-schema","route_parameters":{"_route":"api.info.open-api-schema","auth_required":"0","_controller":"Shopware\\Core\\Framework\\Api\\Controller\\InfoController::openApiSchema","version":"2"},"request_uri":"http://localhost/api/v2/_info/open-api-schema.json","method":"GET"} []

 

Einzig und alleine beim aufrufen eines console commands bekomme ich die folgend Fehlermeldung: 

The "Swag\Bundle\Content\Bundle\Aggregate\BundleTranslation\BundleTranslationDefinition" service or alias has been removed or inlined when the container was compiled. You should either make it public, or stop using the container directly and use dependency injection instead.   

Wie kann ich solches Verhalten besser debugen? Im Error Log ist kein Hinweis auf ein Problem mit dem Service Container.