Thanks for reaching out here in the Community!
Please be advised that channels on Roku are developed and maintained by the channel provider themselves. Since you're getting a specific error message within the Xfinity channel, we would recommend contacting Xfinity's support team to report the issue and get help. There's likely an issue within that one channel that needs to be addressed with an update from them.
We appreciate your understanding.
All the best,
Roku Forum Moderator