There are lots of things that can stop it happening, such as;
missing an update for example base is 4, missed update 5 and now update 6 needs 4 to be updated to 5 first.
Rollback Post to RevisionRollBack
The 3 solutions seem to be RESET / RESTORE FACTORY DEFAULTS / CHECK YOUR REGION. What was the question again? 14 (Yes 14!) accounts supporting my posts for accuracy and help! The ONLY Wombat given a biscuit for great advice! Woohoo!