The information in this article can help you when you are trying to use a passkey to sign in to your Nintendo Account, but it isn't working.
What to do
To sign in using a passkey, you must have previously registered a passkey using a compatible device. If you try to sign in from a device that is not compatible with passkeys, you may receive the message "You can't use a passkey to sign in from this device."
To sign in, please use one of the other sign-in method.
When signing in with a passkey, you must use the device where that passkey is registered. If you try to sign in from a device that is not associated with one of your passkeys, you may receive the message "Couldn't complete passkey sign-in. Please use password sign-in instead."
Please use one of the other sign-in methods, including a different device if you have multiple registered passkeys.
If you have lost or otherwise no longer have access to the device where your passkey is registered, use a different device with a registered passkey or
If you are using the device where the passkey is registered, but for whatever reason the passkey is not working, please contact the appropriate support for your device (Google or Apple) for assistance. In the meantime, you can sign in using one of the other sign-in methods, including a different device, if you have multiple registered passkeys.
Situation not resolved
If you are unable to sign in to your Nintendo Account using one of the alternate sign-in methods, please contact us for additional assistance.