Why do I get an "Underage" error when signing in to Yahoo! Messenger for iPhone?
This article provides assistance for users who experience an "underage" error and cannot sign in to Yahoo! Messenger for iPhone.
Our product team is investigating causes and potential fixes. In the meantime, as a workaround, we recommend using Yahoo! Messenger Mobile through the web browser on your iOS device. This will allow you to continue using our service and to stay in touch with your Contacts.