Harmont docs
APIErrors

passkey_registration_failed

The passkey could not be registered.

HTTP status400
typeinvalid_request
codepasskey_registration_failed
Default messageWe couldn't register that passkey. Try again.

When this happens

The attestation your authenticator returned during sign-up could not be verified. This can follow a mismatched relying-party domain (registering from a different origin than the one the server expects), an authenticator that returns an attestation format the server does not accept, a credential the device declined to create with the required user verification, or a browser extension interfering with WebAuthn.

How to fix it

Start the sign-up again from the official domain and complete the device prompt (PIN or biometric) when asked. If it keeps failing, try a different authenticator or device, or sign in with Google/GitHub and add a passkey from settings afterward. The response message includes a specific reason after the colon, and the server records the underlying cause for support to inspect.

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