Apple Pay domain is not configured
requestApplePayMerchantSession rejected the domain: empty, or contains / or : (not a bare hostname).
Why this happens
Admin Apple Pay domain setting missing or pasted as a full URL. Apple expects a hostname like www.example.com for initiativeContext.
Diagnose and fix
1. Admin → Payment / Authorize.net Apple Pay — set the domain to the bare hostname (no https://).
2. Complete Apple domain verification with Apple and Authorize.net.
3. Retry Apple Pay on Safari/capable devices over HTTPS.
4. Sibling UX: Apple Pay is not available — complete Apple Pay setup.