Many users have reported getting a similar error in the past two days.

Are you able to load the new "Hub" page at https://www.xfinity.com/hub/

And then you click the user-in-circle icon in the upper right corner of the page and get the sign-in form and link to check email at https://xfinityconnect.email.comcast.net/

Which step(s) lead to the error (Hub page, account panel, sign-in, email link)?

This question has been locked because the original author has deleted their account. While you can no longer post new replies, the existing content remains available for reference.