Custom Middleware causing TokenMismatchException Error in Laravel 5.2

I have created a custom middleware with the following code

class UuidMiddleware
{
/**
 * Handle an incoming request.
 *
 * @param  \Illuminate\Http\Request  $request
 * @param  \Closure  $next
 * @return mixed
 */
public function handle($request, Closure $next)
{
    if($request->hasCookie('uuid'))
    {
        return $next($request);
    }
    else
    {
        $uuid = Uuid::generate();
        if (Auth::check())
            $user_id = Auth::user()->id;
        else
            $user_id = '';

        Visitors::create([
            'user_id' => $user_id,
            'uuid' => $uuid
        ]);

        $response = $next($request);
        return $response->withCookie(cookie()->forever('uuid', $uuid));
    }
}

Next I added this middleware in my kernel.php to the web middlewareGroups

protected $middlewareGroups = [
    'web' => [
        \App\Http\Middleware\EncryptCookies::class,
        \Illuminate\Cookie\Middleware\AddQueuedCookiesToResponse::class,
        \Illuminate\Session\Middleware\StartSession::class,
        \Illuminate\View\Middleware\ShareErrorsFromSession::class,
        \App\Http\Middleware\VerifyCsrfToken::class,
        \App\Http\Middleware\UuidMiddleware::class,
    ],

    'api' => [
        'throttle:60,1',
    ],
];

Once I do this, I start getting errors on my login/registration/search etc. As soon as I remove this middleware the error disappears.

The Middleware logic is to check if a cookie named uuid is set. If its not set, it tries to set a uuid in the cookie for the user.

Can someone please help me debug on why this is happening.

via Chebli Mohamed