The actual problem is that the two headers are added with varying information:

// Forwarded Array ( [0] => 46.127.15.xxx ) // X-Forwarded-For Array ( [0] => 82.145.219.118 [1] => 82.145.219.118 [2] => 46.127.15.xxx )

The Forwarded header is missing the IP chain, therefore Symfony throws the exception.