Server Zone Init Failed - after midnight!

Late at night I'm usually just waiting for my explorers to finish their search so I tend to be in another browser tab waiting for the bell telling me they have returned from thier search.

Since the start of the xmas event the game has crashed when I return to the game window after midnight and see the 'Door(s) available' quest arrow from the xmas calander.

Each time I get the popup 'Server Zone Init Failed - The requested zone could not be started'

After reloading the game all is well again.