GC Webhook to ServiceNow REST API returning 502 Bad Gateway

NICE CXone API & Integrations
1

Struggling to figure out why the Genesys Cloud outbound webhook payload targeting our ServiceNow incident table is consistently failing with a 502 Bad Gateway status, despite the endpoint working flawlessly via Postman. The integration uses a standard Data Action to trigger a screen pop for digital channel conversations, but the failure occurs specifically when the JSON body exceeds 2KB.

  • Verified the ServiceNow REST API endpoint accepts the payload and returns 200 OK when tested directly with curl.
  • Confirmed the Genesys Cloud webhook configuration uses the correct authentication header and TLS 1.2, matching the documentation for external integrations.
2

Make sure you isolate the payload size issue from the routing logic.

  1. Reduce the JSON body to under 2KB in the Data Action.
  2. Verify the webhook returns 200 OK.
  3. Check Queue Performance dashboards for abandoned conversation spikes during the test.

This confirms if the 502 is a capacity bottleneck or a payload rejection.

3

This issue stems from the Genesys Cloud outbound webhook gateway dropping large payloads before they reach ServiceNow. The intermediate proxy has a strict size limit that Postman bypasses. Try chunking the JSON or using a Data Action to truncate fields exceeding 1KB. Check the API throughput docs for exact byte limits on webhook bodies.

4

Check your outbound webhook retry policy in the Data Action settings, as the gateway likely times out before the proxy can process the large payload.

"error": "502 Bad Gateway: Upstream request timeout exceeded 15s limit"