Doorkeeper does not support / allow non-secure redirect URIs due to potential security risk.
So, Doorkeepers gem now forces use of secure redirect URLs. Since OAuth2 delegates its security to HTTPS. In general – this is not a bad idea, however sometimes you will have to use non-secure redirect URI due to a fact that one server doesn’t have SSL setup.
To allow use of unsecure redirect URIs, all you need to do is change doorkeeper initializer found in