Illuminate\Contracts\Container\BindingResolutionException: Target class [App\Http\Controllers\ReadingsController] does not exist. in code example

Example 1: Illuminate\Contracts\Container\BindingResolutionException Target class [SlugController] does not exist.

Route::get('/test/{slug}',  'App\Http\Controllers\SlugController@show' );

Example 2: Illuminate\Contracts\Container\BindingResolutionException Target class [PagesController] does not exist.

Target class [PagesController] does not exist.