channel_window_closed
HTTP status: 422 (Unprocessable)
Title: Channel window closed
Cause
More than 24 hours passed since the last message of the person and WhatsApp only accepts approved templates now. The message was not sent.
How to fix it
Send an approved WhatsApp template instead of free text. List the templates first.
Call the endpoint named below first, then send the request again.
Endpoint: GET /v2/whatsapp/templates
Every error carries requestId and the Request-Id header. Send it when you write to support.