The latest update of UCM makes use of new features only available in PHP version 5.3 and above.
We have dropped support for PHP version 5.2, and most parts of the system will stop working.
Everybody still using PHP 5.2 will have to swap to 5.3 or above. Your hosting provider can generally perform this swap for you very easily.
(most people should be running 5.3 or above anyway)