"Manage My Reservation" Rescheduling Error

Hi there. I am unable to reschedule my Genius Bar technical support appointment via the email "Manage My Reservation" link. I have to contact Apple Support via Chat and the person at the other end reschedules the appointment for me. The rescheduling error occurs whether I am on the Windows laptop, iPhone, or Android tablet.

Here's what happens:

1. Click on the "Manage Your Reservation" link in the "Your upcoming Genius Bar appointment." email.

2. In the "Here are the details of your case" web page, click on Reschedule button.

3. A calendar popup appears. Select the date and time for the rescheduled appointment.

4. The following error appears:

"We’re Sorry.

We are unable to complete your request at this time. Please try again or come back later.

270ce63f-f78f-49cf-a7f9-7b932b4ee627 "

The bottom string that appears changes whenever I try to reschedule.

Any ideas why I am receiving this error? Thanks.

P.S. I cannot locate the proper Community to post this, so I chose "Apple ID".