Undefined Constant illuminate\http\request::header_x_forwarded_all When Upgrading

[dbarzin]

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.

// Before...
'headers' => Illuminate\Http\Request::HEADER_X_FORWARDED_ALL;

// After...
 'headers' => 
    Illuminate\Http\Request::HEADER_X_FORWARDED_FOR | 
    Illuminate\Http\Request::HEADER_X_FORWARDED_HOST | 
    Illuminate\Http\Request::HEADER_X_FORWARDED_PORT | 
    Illuminate\Http\Request::HEADER_X_FORWARDED_PROTO | 
    Illuminate\Http\Request::HEADER_X_FORWARDED_AWS_ELB,

Source : (https://laravel.com/docs/9.x/upgrade#upgrade-9.0)