A passkey addition failure occurs on iOS when attempting to save an Auth0 passkey using Microsoft Authenticator because the application only supports Microsoft Entra ID passkeys. Resolve this issue by using a general-purpose passkey provider and disabling Microsoft Authenticator as a system-wide provider in iOS settings. When an attempt to save an Auth0 passkey occurs, Microsoft Authenticator generates the following error:

Failed to add passkey
Microsoft Authenticator doesn't support this passkey.

• Auth0
• Passkeys
• Microsoft Authenticator
• iOS

Microsoft Authenticator registers as a system-wide Fast IDentity Online 2 (FIDO2) and Web Authentication (WebAuthn) provider on iOS. When an application requests to save a passkey, iOS presents Microsoft Authenticator as an available option because iOS cannot determine if the credential is for a Microsoft corporate account or a third-party site. However, Microsoft Authenticator only supports passkeys for Microsoft Entra ID, as detailed in the Microsoft Authenticator Passkey FAQ.

How is the Microsoft Authenticator passkey error resolved?

Resolve the passkey error by using an alternative provider and disabling Microsoft Authenticator in the device settings.

• Use a general-purpose passkey provider instead of Microsoft Authenticator to save and use passkeys for Auth0 applications.
• Turn off Microsoft Authenticator system-wide in iOS settings to prevent it from appearing in the passkey provider list.