8 September 2026
A precise error when WhatsApp cannot find the recipient, and purchased slots that apply themselves.
422 recipient_not_on_whatsapp on POST /messages
Improvement. When WhatsApp reports that it has no account for the recipient,
the send now answers 422 with the code recipient_not_on_whatsapp and a message
that says what to check: the number must be in international format (country
code first, no leading zero) and the person must use WhatsApp. Until today this
case came back as a generic 502 send_failed, which read like an outage on our
side. It is permanent for that number — fix the input rather than retrying.
502 send_failed is now reserved for failures that are not about the recipient
(session or provider), where a short back-off and a retry make sense. Both codes
are listed in Errors & idempotency.
Purchased slots apply themselves
Improvement. In a developer workspace, a new connection now takes a free purchased slot immediately instead of starting a trial, and a connection still on trial is upgraded as soon as a slot is free. On the Connections & Billing page you can also move capacity by hand: "Assign a slot" on a trial or expired connection, "Release slot" on a slot-backed one (the slot returns to your pool with its remaining time), and a "free slots" counter on the Slots card.