Error when trying to register on feedburner. What could be the problem?

Question

RSS

registration fails on Feedburner. I enter the address:

I click "Next" and the following error pops up:

What could be the problem?
Google does not find a solution, only questions.
At the same time, I tested the site on a different domain, everything works there.
All sites on WP

Answer 1

The solution was to disable the maintenance mode