Answers for "Target class [App\Http\Controllers\AuthController] does not exist."

Target class [UserController] does not exist.

Note: don't forget to import (use) your controller in the routes(web.php) file at the top. Like:
use App\Http\Controllers\PagesController;

Route::get('/',[PagesController::class, 'index']);

Target class [App\Http\Controllers\Request] does not exist.

use Illuminate\Http\Request;

Target class [App\Http\Controllers\EmployeeController] does not exist.

[PagesController::class, 'index']

Target class [AppController] does not exist.

public function boot()
{
    ...

    Route::prefix('api')
        ->middleware('api')
        ->namespace('App\Http\Controllers') // <---------
        ->group(base_path('routes/api.php'));

    ...
}