Controllers under subfolder

1. Remove this class map which you have set.
   
2. Your real namespace should be something as 
   
   Code:

   namespace App\Controllers\Ajax;
3. Make the first letter of ajax capital at all places - this is the standard applied to CI.
   
4. At App/Config/Routes check if you have set 
   
   Code:

   $routes->setDefaultNamespace('App\Controllers');
$routes->setAutoRoute(true);
   - at least with the current CI 4 version at the repository they are set .
   

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