No easy answer for "Failed to generate XML-formatted config". Hive manager bug, some policy or setting has corrupt or has a invalid setting. In my case "QoS policies" caused issues applying firewall polices, I simply detached the QoS policy from the config. For you, it's probably going to be something else, probably related to the last change you made prior to receiving the error. Try starting with a new config, duplicating settings from your old, trial and error. If you call tech support, that is what they would do.
