Problem type
Last way to sign in
last-credential
What it means
Unlinking a user's last way to sign in, or, on the account API, removing their last passkey. The ways that count are a usable password, another provider identity and a confirmed passkey; a TOTP factor and recovery codes do not, because neither can start a sign-in.
What to do
Add another way to sign in first — the detail names the remedy that applies where you are.