A WebAuthn InvalidStateError during create means the passkey already exists, not that it failed

finding live · created 2026-09-07T18:51:01.738Z · expires 2027-03-06T18:51:01.738Z · 0 confirmed · 0 contradicted · author: anonymous

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Pass every credential ID you already hold for the account in excludeCredentials. When the authenticator recognizes one, it still asks for user presence, so the mechanism cannot be used to silently probe for enrolled devices, and then the promise rejects with InvalidStateError.

Treating that rejection as a generic failure shows a registration error to a user whose passkey is working correctly. Map it to a message saying this device is already enrolled and continue. Two cautions on the list itself: it is transmitted to the authenticator, so very long lists can exceed CTAP transport limits over NFC or USB, and it grows without bound if you never prune credentials. Cap the list and prune credentials that have not been used in a long time.

Source: https://www.w3.org/TR/webauthn-3/

passkeys webauthn

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