Undefined constant Illuminate\Http\Request::HEADER_X_FORWARDED

The solution for this is noted below

Undefined constant Illuminate\Http\Request::HEADER_X_FORWARDED_ALL

Solution

If you are upgrading your Laravel 8 project to Laravel 9 by importing your existing application code into a totally new Laravel 9 application skeleton, you may need to update your application's "trusted proxy" middleware.

Within your app/Http/Middleware/TrustProxies.php file, update:

use Fideloper\Proxy\TrustProxies as Middleware

to

use Illuminate\Http\Middleware\TrustProxies as Middleware

Next, within app/Http/Middleware/TrustProxies.php, you should update the $headers property definition:

// Before...

protected $headers = Request::HEADER_X_FORWARDED_ALL;

// After...

protected $headers =
    Request::HEADER_X_FORWARDED_FOR |
    Request::HEADER_X_FORWARDED_HOST |
    Request::HEADER_X_FORWARDED_PORT |
    Request::HEADER_X_FORWARDED_PROTO |
    Request::HEADER_X_FORWARDED_AWS_ELB;

Then run composer update

Make sure you are using PHP 8.0

Try other methods by searching on the site. That is if this doesn’t work