Update base.php

"Invalid Class Name" error does occur when using directory and file naming structure like
App\Controllers\
App\Controllers\Authenticator.php

The autoloader will look for "app/controllers/authenticator.php" instead of "App/controllers/Authenticator.php"
These few lines of code will create another string of uppercase class name and path, then included it in the file existence checking.

I had this problem while working on a big project which works fine on my development PC and doesn't work on my live Web Server.

This is the workaround that fixed the problem.