It's not a hotfix, nor is it an update. . .
Taken from maintenance announcement:
At the following time, we will be performing maintenance on the Square Enix Account Management System. During this period, FINAL FANTASY XIV and other related services will be unavailable. Please see below for a list of unavailable services and its time frames.
This process has taken upto 7.5hrs in the past and with server transfers for EU still rolling out in waves, it can easily hit 10 hours and beyond.