Can't login to iCloud with AppleTV

You're welcome.

As for the "how would you find out" bit , It is documented here. An older Apple TV is using "older" software.

Two-factor authentication for Apple ID - Apple Support

I believe this "procedure" has been replaced by an app specific password >> Using app-specific passwords - Apple Support

Either way should work.

Thank you so much. Nothing like having your own photos streaming across the television screen. Your advise successfully got me into my iCloud on my Apple TV by putting in the validation code after my password. Headache averted.

Are you using 2 Factor Authentication or 2 Step Verification on your Apple ID?

If you get a prompt and code, you are using something.

On your Apple TV, enter your password followed by that code.

So your password is Apple123 and the code is f789, type Apple123f789 into your Apple TV.

Thank you!!! I just don't understand , how was I suppose to know that ,IF you didn't post this^^^^ Thank you Much appreciated!!!

Very cool, I will read up on that. but just want to say thanks again for sharing your knowledge , you saved me a headache! Have a good one!!

Thank you for the followup!

Excellent. Seems an App specific password would not work, but this method did. Thanks for the post.