I have recently upgraded directly from Snow Leopard to Mountain Lion and ever since, Time Machine gives an error when it tries to backup. The error is: The network backup disk does not support the required AFP features. Open Time Machine preferences to select a different backup disk. Prior to the upgrade, Time Machine worked perfectly OK and even now, I can see previous backups. The device it is trying to back up to is a wireless MyBook Live from Western Digital. And I can read and write to the drive from my iMac perfectly OK. I called Apple support about this (as I had just purchased Mountain Lion) but they did not seem too interested as I had not purchased a support package. They mumbled something about it not being an Apple hardware device and that was it. When I asked what the message about the required AFP features meant, the poor guy did not know and wasn't really very helpful in finding out it's meaning. Hopefully, some can shed some light on this as I am now running without backups.