Authentication and authorization errors
401 Unauthorized: the API key is invalid or revoked. Verify the API key in your environment is correct and hasn't expired.
403 Forbidden: you have a valid API key but don't have permission for the requested operation.
Message sending errors
400 with 'recipient not on WhatsApp': the recipient phone number doesn't have WhatsApp active.
400 with 'template not found': the template name in the payload doesn't match any approved template. Template names are case-sensitive.
429 Too Many Requests: you've exceeded the API rate limit. Implement exponential backoff.
Webhook errors
Webhook not received: verify your endpoint is publicly reachable (not localhost), responds with 200 OK within 20 seconds, and the signature in the header is correctly verified.
Debug tools
Use the Chat API dashboard to monitor sent messages and their statuses.
For local testing, use ngrok to expose your local webhook endpoint.
