Won't sync online data

When i go into my game, it will come up with an error and say that it is unable to sync data and tells me to play offline.

i fixed it

How did you fix? I am encountering the same issue.

Nevermind, managed to fix this by logging out of my Xbox Live Account, then going offline in Xbox Network Settings, then shutting down my Xbox, then unplugging it and plugging it back in, then going back online in Settings, then loading up Halo.