I changed the URL of my discourse site, and promptly members started complaining that they could not log in. Exactly the problem reported in Changing domain names prevents Discourse ID from working. Looks like the fix is to empty the credentials via the rails console.
I thought the Regenerate credentials button would help but selecting that generated an error as well.
Seems to me this is worth investing in addressing, since it’s not unheard of to change the URL of your site. My feeling is that Discourse ID should auto correct itself in some way. Or at least there should be a way to refresh Discourse ID via the admin UI.
Failing that, I’d suggest adding a note linking here from Change the domain name or rename your Discourse.