Illuminate\Contracts\Container\BindingResolutionException Target class [IndexController] does not exist. code example

Example 1: Illuminate\Contracts\Container\BindingResolutionException target calss does not exist

Routing namespaces have been updated on Laravel 8.X

On your router, you should define:
use App\Http\Controllers\TestController;

And then, declare:
Route::get('test',[TestController::class, 'test']);

Example 2: Illuminate\Contracts\Container\BindingResolutionExceptionTarget class [ProjectController] does not exist.

# ajouter le controller
use App\Http\Controllers\ProjectController;


Route::resource('/projects', ProjectController::class);