Frelorn, of Turbine's Asheron's Call Community Team, posted an announcement regarding a delay of the December event:
Due to operational constraints and stability issues with the December Patch, Turbine has made the decision that delaying the December update until January is in everyone's best interest. We know this will be disappointing for those players who enjoy our monthly content, but after weighing all of our options we feel that this is the right decision given the circumstances.
In the meantime, our live events staff will be providing more events over the remainder of December and into January. Our goal with these in-game events is not only to have fun with current players, but also let those players who may return to us over the Holidays see what our live events team has been up to!
My personal opinion is "better late than broken"!