Registration could not be completed
Signup (email API or OAuth create-user path) failed with a generic Registration could not be completed. Often used when ban/signup blocks apply or account creation errors are not more specific.
Why this happens
AUTH_REGISTRATION_FAILED / oauth_registration_failed: IP/email ban blocking signup, unexpected create failure, or OAuth registration path returning this code. Distinct from Registration is currently disabled (feature off) and from validation messages (invalid email, captcha, etc.).
Diagnose and fix
1. Confirm Registration enabled is on.
2. Check bans / banned mail hosts / signup IP bans.
3. Review captcha and email rules on the register form.
4. App logs for the register/OAuth create path; retry after fixing the root cause.
5. If the page says registration is closed, see the disabled sibling article.