Just had this issue happen.
I changed the hostname of my self-hosted Discourse, and when I went to log back in, I got an error saying: “Incorrect username, email or password”
The only way I can log in with the same user is by having Discourse send a link to my email.
Any ideas about what happened here?
maybe you are using the browser password manager instead of typing it in? (password saved will be domain dependent).
I am not sure. I have changed host names without the issue you describe
@Isambard suggestion sounds highly likely. You can search your password manager for the old domain name. Otherwise try a password reset email and try changing password & then try logging in
Otherwise can you post more details?