NotAllowedError and AbortError
Distinguish user cancellation from RP ID, timeout, transport, or policy issues.
Conditional UI
Fix passkey autofill and conditional mediation not appearing in Chrome, Safari, Android, and iOS.
Cookie migration
Debug third-party cookie phaseout, CHIPS, Partitioned cookies, and SameSite=None requirements.
RP ID and allowCredentials
Catch domain, subdomain, credential ID, and authenticator mismatch problems.