Could not allocate a WebMoney payment number — try again
WebMoney checkout tried several random payment numbers; each collided with an existing payment.externalId for WMZ/WMT. After retries, it throws this error.
Why this happens
Extremely unlikely collision storm, or DB uniqueness pressure. Not a purse-misconfiguration message (those say purse/checkout not enabled).
Diagnose and fix
1. Member: retry checkout once or twice.
2. Admin: if it persists, inspect WebMoney payments for stuck/duplicate external IDs; check generator health.
3. Confirm WebMoney (WMZ / WMT) purse and secret are configured.
4. Offer another payment method meanwhile.