Apple has sent out a notice stating that new apps and app updates will not be accepted on Friday, December 23 through Tuesday December 27, 2016.
This shutdown only affects creating items in iTunes Connect and delivering new apps and app updates to customers. Customers with existing apps will continue to receive content hosted by Mag+ or by their own hosted servers.
This shutdown will not affect the ability to build iOS apps in the Mag+ Publish portal nor to build Android/Kindle Fire apps.
Please see Apple's notice here.