Some of the deployments for our API client are not on publicly available networks. This was previously fine, for example for our development client I could use e.g. https://dev-server.internal/ebay/token/success in the accept URL. This would then redirect fine. With the new Interface, this shows as an invalid URL, however older RuNames with internal URLs still work. Whilst a warning might be useful, it should be possible to submit a url even if it fails this check.