3D Secure is unavailable
Authorize.net 3DS client loaded Songbird but window.Cardinal was missing, or a challenge path rejected with the same message.
Why this happens
Script blocked, wrong Songbird URL, ad blocker, or incomplete Cardinal bootstrap. Distinct from 3D Secure could not be initialized (JWT/setup failure) and from bank challenge failures later in the flow.
Diagnose and fix
1. Hard refresh; allow scripts from Authorize.net / Cardinal domains.
2. Admin: verify 3DS enabled, Songbird URL, and API credentials under Authorize.net.
3. Try another browser; disable strict blockers for checkout.
4. See Common payment failures if cards still fail after Cardinal loads.