I get the request to sign into messages when I start messages, but get an error every time I try (many times over the past few days...). Any clues?

Hi g21962,

welcome to the Apple (user-to-user) Community.

Re: "sign in to messages" : "error every time" : Any Clues ?"

Apple support have articles online (links below) that may help:

How to: Set up Messages on Mac - Apple Support

and

What to do: If you can't sign in to your iMessage account or FaceTime on your Mac

________

If needed:

If you want, you can contact Apple Messages Support:

There is a link to Support staff at bottom right on the webpage that opens from the link below.

Messages for iPhone, iPad, Apple Watch, and Mac - Official Apple Support

All the best :-)