A problem can be that you try to access you session inside of your controller's __constructor() function.
From Laravel 5.3+ this is not possible anymore because it is not intended to work anyway, as stated in the upgrade guide.
In previous versions of Laravel, you could access session variables or the authenticated user in your controller's constructor. This was never intended to be an explicit feature of the framework. In Laravel 5.3, you can't access the session or authenticated user in your controller's constructor because the middleware has not run yet.
For more background information also read Taylor his response.
Workaround
If you still want to use this, you can dynamically create a middleware and run it in the constructor, as described in the upgrade guide:
As an alternative, you may define a Closure based middleware directly in your controller's constructor. Before using this feature, make sure that your application is running Laravel 5.3.4 or above:
<?php namespace App\Http\Controllers; use App\User; use Illuminate\Support\Facades\Auth; use App\Http\Controllers\Controller; class ProjectController extends Controller { /** * All of the current user's projects. */ protected $projects; /** * Create a new controller instance. * * @return void */ public function __construct() { $this->middleware(function ($request, $next) { $this->projects = Auth::user()->projects; return $next($request); }); } }