Disney has added the following announcement to the bottom of its online booking page:
“Please be advised that we will be updating our systems to serve you better. During this enhancement, beginning on October 12 at 4 p.m. ET, online bookings and bookings through the Disney Reservation Center will be unavailable. We expect to return to full functionality by the morning of October 14. We apologize in advance for any inconvenience. Please note that these dates and times are subject to change.”
This means that Disney will be unable to make changes to a reservation or create a new reservation between those times, either online or by phone.