Why won't a saved passkey autofill into the login field?

I wired up conditional UI exactly like the docs show, and on some browsers the saved passkey never appears in the username field at all.

IntermediateRead 6 minDoing: an afternoon6 steps

▶ Start

What you'll have at the end

A username field where a stored passkey shows up in the browser's own autofill list, cancelled cleanly if the user starts typing instead.

Before you start

You need

A login field that already carries some form of the autocomplete value naming webauthn, a conditional-mediation request already wired up when the page loads, a stored flag recording whether each registered passkey came back as a discoverable credential, and at least one visitor who has already registered one.

Not covered

Building the explicit 'sign in with a passkey' button and its own fallback screen for a machine where conditional UI is genuinely unsupported.

Leans on

6 steps

Where to go next

Gate a passkey button behind a real support check

go there to build the explicit button and fallback screen for a machine that genuinely can't do this.

Rehearse a passkey flow in Chrome's DevTools

go there to reproduce a machine's exact behavior without needing to own that hardware yourself.

Checked 22 Aug 2026

Part of the Web Authentication and Passkeys cookbook