Fatal error: Class 'App\Http\Controllers\Controller' not found

I am getting this error of Controller not found even though my Controller class is present in my Controllers namespace.

<?php
namespace App\Http\Controllers;

use App\Http\Controllers\Controller;



class UserController extends Controller
{

    public function SignIn(Request $request){
        if(Auth::attempt(['usernameEmail'=>$request['usernameEmail'],'password'=>$request['password']])){
            return redirect()->route('dashboard');
        }
        return redirect()->back();
    }

    public function getDashBoard(){
        return view('dashboard');
    }
}

via Chebli Mohamed