Registering an application redirectURI return HTTP 403

Hi!
I have registered a test application for testing the OAuth2 authentication. I have created a web type key, but when I want to add a redirectURI for it, the browser returns 403 forbidden. If the URI starts with http:// or https:// I always get the error, but if it starts without it, there is no error, it saves just fine:

127.0.0.1:9999/callback → saves fine
http ://127.0.0.1:9999/callback → http 403

Did anyone encounter this issue? Is there a workaround to save the URI starting with http?