91305: Sink endpoint rejected the event

Twilio records this error when Event Streams attempts to deliver an event, but the target sink endpoint rejects the payload with an HTTP 4xx status code.

Because a 4xx response indicates a client-side or configuration error, Twilio does not attempt to retry delivery for these events.

• Authentication or authorization failures (401 / 403): API keys, credentials, or signing signatures configured on the sink are invalid or expired.
• Invalid endpoint URL (404): The URL path configured on the sink is incorrect or the target route no longer exists.
• Payload or header rejection (400 / 415): The sink endpoint rejected the payload structure, missing parameters, or the Content-Type header sent by Twilio.
• WAF or firewall blocking: A Web Application Firewall (WAF), CDN, or bot protection layer blocked the incoming request before it reached your service application.

• Inspect sink endpoint's logs to review the full request payload, headers, exact status code, and response body returned to Twilio.
• Verify that any API keys, tokens, or signing secrets configured on the sink match your sink's requirements.
• Confirm that the destination URL and path configured on the sink are active and correctly routed.
• If your endpoint sits behind a WAF or CDN, update firewall and WAF rules to ensure Twilio's IP ranges are allowed.
• Ensure your endpoint is configured to parse the content type (e.g., application/json) transmitted by Twilio for this sink type.

• 91300: Event delivery to sink failed
• 91306: Sink endpoint returned a server error

• Event Streams overview
• Sink resource
• Subscription resource