Answers for "laravel auth not found in controller.php"

Auth' not found

To fix this, add use Auth; at the top of your Controller file along with your other use statements or alternatively prefix all instances of Auth with backslash like this: \Auth to let PHP know to load it from the global namespace.

Route::auth(); giving error in laravel 7

Do this step from the upgrade guide 
https://laravel.com/docs/7.x/upgrade#authentication-scaffolding

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composer require laravel/ui "^2.0"