BTCPay checkout is not configured
Checkout route selected BTCPay but the integration is not ready (balanceTopUp.btcpayNotConfigured / 503). Short sibling of the “not enabled — add server URL…” message.
Why this happens
BTCPay toggle off or server URL / store ID / API key incomplete. Distinct from BTCPay Server did not return a checkout link (configured but invoice create failed).
Diagnose and fix
1. Admin → Settings → Payment → BTCPay Server — set URL, store ID, API key; enable checkout.
2. Retry premium / balance / traffic crypto checkout.
3. Offer another gateway (NOWPayments, card, etc.) if BTCPay is not intentional.
4. See BTCPay Server for setup details.