Laravel 5.6 TrustedProxies error

After some investigation (Winmerge comparison with a fresh install of Laravel 5.6) this comes down to a difference in the files app\Http\Middleware\TrustProxies.php:

Laravel 5.5:

namespace App\Http\Middleware;use Illuminate\Http\Request;use Fideloper\Proxy\TrustProxies as Middleware;class TrustProxies extends Middleware{    /**     * The trusted proxies for this application.     *     * @var array     */    protected $proxies;    /**     * The current proxy header mappings.     *     * @var array     */    protected $headers = [        Request::HEADER_FORWARDED => 'FORWARDED',        Request::HEADER_X_FORWARDED_FOR => 'X_FORWARDED_FOR',        Request::HEADER_X_FORWARDED_HOST => 'X_FORWARDED_HOST',        Request::HEADER_X_FORWARDED_PORT => 'X_FORWARDED_PORT',        Request::HEADER_X_FORWARDED_PROTO => 'X_FORWARDED_PROTO',    ];}

Laravel 5.6:

namespace App\Http\Middleware;use Illuminate\Http\Request;use Fideloper\Proxy\TrustProxies as Middleware;class TrustProxies extends Middleware{    /**     * The trusted proxies for this application.     *     * @var array     */    protected $proxies;    /**     * The headers that should be used to detect proxies.     *     * @var string     */    protected $headers = Request::HEADER_X_FORWARDED_ALL;}

Ergo, set protected $headers = Request::HEADER_X_FORWARDED_ALL; as per Laravel 5.6 version

Open app\Http\Middleware\TrustProxies.php.

Change the following

protected $headers = [    Request::HEADER_FORWARDED => 'FORWARDED',    Request::HEADER_X_FORWARDED_FOR => 'X_FORWARDED_FOR',    Request::HEADER_X_FORWARDED_HOST => 'X_FORWARDED_HOST',    Request::HEADER_X_FORWARDED_PORT => 'X_FORWARDED_PORT',    Request::HEADER_X_FORWARDED_PROTO => 'X_FORWARDED_PROTO',];

to

protected $headers = Request::HEADER_X_FORWARDED_ALL;

As stated in the upgrade guide, you need to set the $headers property in App\Http\Middleware\TrustProxies to a bit property.

The constants are defined in Symfony\Component\HttpFoundation\Request.

const HEADER_FORWARDED = 0b00001; // When using RFC 7239const HEADER_X_FORWARDED_FOR = 0b00010;const HEADER_X_FORWARDED_HOST = 0b00100;const HEADER_X_FORWARDED_PROTO = 0b01000;const HEADER_X_FORWARDED_PORT = 0b10000;const HEADER_X_FORWARDED_ALL = 0b11110; // All "X-Forwarded-*" headersconst HEADER_X_FORWARDED_AWS_ELB = 0b11010; // AWS ELB doesn't send X-Forwarded-Host

In the upgrade guide, HEADER_X_FORWARDED_ALL is used but you can use a combination of the bit values.