Same issue

If you have a Roku, add the Xfinity Stream app to it as a workaround. I have a Samsung that's 2 years old and can watch live TV again. 

Hello @user_hg8i48, thank you for taking the time to reach out on social media.  I understand your concern with the error, and I'd like the opportunity to check into that for you.

To access your account, will you please send us a direct message with your full name and complete service address to “Xfinity Support”. To do so, click on the chat icon located at the top right of this forums page.

Here's the detailed steps to direct message us:

• Click "Sign In" if necessary
• Click the "Direct Message” icon (upper right corner of this page)
• Click the "New message" (pencil and paper) icon
• Type "Xfinity Support" in the to line and select "Xfinity Support" from the drop-down list
• Type your message in the text area near the bottom of the window
• Press Enter to send your message