Laravel5 status 500

I've been trying to import an existing Laravel project on the Cloud9 IDE. I set up and installed everything required but fail to load the web. The developer console shows "Failed to load resource: the server responded with a status of 500 (Internal Server Error)"

Lot of people said it is about the written permission for the "storage" and "bootstraps" folder, so I gave written permission for all files in the whole workspace, but still it gave the same error. I checked the apache error log but can't see the corresponding log. Also, normal PHP files(hello world) are loaded successfully but not the Laravel related pages. The code of public/index.php:

require DIR.'/../bootstrap/autoload.php';

$app = require_once DIR.'/../bootstrap/app.php';

$kernel = $app->make(Illuminate\Contracts\Http\Kernel::class);

$response = $kernel->handle( $request = Illuminate\Http\Request::capture() );

$response->send();

$kernel->terminate($request, $response);

The status 500 error appears on $response->send();

via Chebli Mohamed