Invalid WebMoney signature
WebMoney payment result/callback failed signature verification. The site will not mark the payment paid.
Why this happens
Wrong purse secret key in Admin Payment settings, test/live mismatch, or altered POST fields. Same idea as NOWPayments Invalid IPN signature.
Diagnose and fix
1. Admin → Settings → Payment → WebMoney — confirm WMZ/WMT purse and secret key match the merchant cabinet.
2. Ensure result URL points at this site over HTTPS.
3. Retry a small test payment; inspect WebMoney and app logs.
4. See WebMoney (WMZ / WMT) for setup.