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)?