Class App\Api\v1\Controllers\SecondaryStudentController does not exist

I created an API with Lumen and on my localhost, everything works fine but on my production server, i keep getting this error message whenever i try to access a route:

Class App\Api\v1\Controllers\SecondaryStudentController does not exist

Initially i thought it might be a version issue. On my local machine, i make use of PHP 7.1 so i tried downgrading the PHP version of my production server from 7.2 to 7.1 but still get this error.

I don't know what else to do because it works fine on local server.

This is the web.php file

Route::group(['namespace'=>'App\Api\v1\Controllers' , 'prefix' => 'api/v1'], function () {

    // Secondary Student route
    Route::group(['prefix' => 'secondarystudent'], function () {
        Route::post('create' , 'SecondaryStudentController@create');
    });

});

This is the SecondaryStudentController.php

    namespace App\Api\v1\Controllers;
    use Illuminate\Http\Request;
    use App\Api\v1\Repositories\SecondaryStudentRepository;

    class SecondaryStudentController extends Controller
    {

      /**
       *
       * @var object
       */
      private $secondary_student;


      /**
       * Class constructor
       */
      public function __construct(SecondaryStudentRepository $secondary_student)
      {
          $this->secondary_student = $secondary_student;

      }


      /**
       *
       * @param object $request
       *
       * @return JSON
       *
       */
      public function create (Request $request)
      {

          try {

              $secondary_student = $this->secondary_student->create($request);

              // Create a custom array as response
              $response = [
                  "status" => "success",
                  "code" => 200,
                  "message" => "Ok",
                  "data" => $secondary_student
              ];

              // return the custom in JSON format
              return response()->json($response);

          } catch (\Exception $e) {

            // Create a custom array as response
            $response = [
                "status" => "failed",
                "code" => 404,
                "message" => "Error! Sorry server could not process this request",
                "data" => NULL
            ];

            // return the custom in JSON format
            return response()->json($response);

          }

      }
    }

This is the bootstrap/app.php

<?php

require_once __DIR__.'/../vendor/autoload.php';

try {
    (new Dotenv\Dotenv(dirname(__DIR__)))->load();
} catch (Dotenv\Exception\InvalidPathException $e) {
    //
}

/*
|--------------------------------------------------------------------------
| Create The Application
|--------------------------------------------------------------------------
|
| Here we will load the environment and create the application instance
| that serves as the central piece of this framework. We'll use this
| application as an "IoC" container and router for this framework.
|
*/

$app = new Laravel\Lumen\Application(
    dirname(__DIR__)
);

$app->withFacades();

$app->withEloquent();

/*
|--------------------------------------------------------------------------
| Register Container Bindings
|--------------------------------------------------------------------------
|
| Now we will register a few bindings in the service container. We will
| register the exception handler and the console kernel. You may add
| your own bindings here if you like or you can make another file.
|
*/

$app->singleton(
    Illuminate\Contracts\Debug\ExceptionHandler::class,
    App\Exceptions\Handler::class
);

$app->singleton(
    Illuminate\Contracts\Console\Kernel::class,
    App\Console\Kernel::class
);

/*
|--------------------------------------------------------------------------
| Register Middleware
|--------------------------------------------------------------------------
|
| Next, we will register the middleware with the application. These can
| be global middleware that run before and after each request into a
| route or middleware that'll be assigned to some specific routes.
|
*/

// $app->middleware([
//     App\Http\Middleware\ExampleMiddleware::class
// ]);

$app->routeMiddleware([
    'auth' => App\Http\Middleware\Authenticate::class,
]);

/*
|--------------------------------------------------------------------------
| Register Service Providers
|--------------------------------------------------------------------------
|
| Here we will register all of the application's service providers which
| are used to bind services into the container. Service providers are
| totally optional, so you are not required to uncomment this line.
|
*/

// $app->configure('mail');
$app->register(App\Providers\AppServiceProvider::class);
$app->register(App\Providers\AuthServiceProvider::class);
// $app->register(Illuminate\Mail\MailServiceProvider::class);
// $app->register(App\Providers\EventServiceProvider::class);

/*
|--------------------------------------------------------------------------
| Load The Application Routes
|--------------------------------------------------------------------------
|
| Next we will include the routes file so that they can all be added to
| the application. This will provide all of the URLs the application
| can respond to, as well as the controllers that may handle them.
|
*/

$app->router->group([
 
], function ($router) {
    require __DIR__.'/../routes/web.php';
});

return $app;