Data Action 502 Bad Gateway on ServiceNow Incident Create with Large Attachments

Anyone know why the Genesys Cloud Data Action integration returns a 502 Bad Gateway error specifically when the payload includes a base64-encoded attachment exceeding 2MB? The integration uses the standard ServiceNow REST API endpoint (/api/now/table/incident) and has functioned correctly for months with smaller text-based payloads. The error occurs intermittently during peak hours in the Europe/London timezone, suggesting a potential timeout or load balancer issue rather than a configuration error.

The Architect flow constructs the JSON body using a Set Data node, mapping the transcript and metadata fields correctly. The webhook logs indicate that the request is successfully initiated from the Genesys Cloud side, but the response from ServiceNow is truncated or malformed. Inspecting the HTTP headers in the Data Action diagnostic logs reveals a Connection: close header from the upstream proxy, which is unusual for standard REST API interactions. The ServiceNow instance is on the Washington DC release, and the integration user has full administrative privileges with no rate limits currently enforced.

We have verified that the same payload works when tested directly via Postman using the identical OAuth2 token generated by the Genesys Cloud integration. This isolates the issue to the Genesys Cloud Data Action execution environment or the intermediate network path. The error code 502 suggests that the Genesys Cloud server acting as a reverse proxy for the outbound request received an invalid response from the ServiceNow server, or the connection was dropped before completion. The timeout settings in the Data Action are set to the default 30 seconds, which should be sufficient for this operation.

Is there a known limitation regarding payload size or binary data handling in the current version of the Data Action service? We are considering implementing a chunking mechanism or using a separate Azure Function to handle the attachment upload, but we want to confirm if this is a platform constraint first. Any insights into the specific behavior of the Genesys Cloud outbound proxy when handling large base64 strings would be appreciated.

It depends, but typically the 502 error here isn’t a gen issue. it’s the service side choking on the payload size or the connection dropping while waiting for that large base64 blob to parse. when dealing with legal holds or large attachments, direct api posts are risky. the timeout varies by load balancer config, often 30-60 seconds, which gets eaten up quickly by encoding overhead.

try splitting the workflow. instead of attaching the base64 string directly to the incident create payload, upload the file to an s3 bucket first using the recording api or a separate data action. then, pass the signed url or the s3 object key to the service incident. this keeps the payload tiny and avoids the gateway timeout.

if you must inline it, check the service api limit. some instances cap json payloads at 4mb or 10mb. also, ensure the content-type header is strictly application/json. if the base64 string has line breaks or special characters, the json parser might fail before the gateway even sees it.

here is a quick python snippet to validate the payload size and structure before the post:

import json

payload = {
 "short_description": "test",
 "u_attachment": large_base64_string
}

# check size in bytes
payload_bytes = json.dumps(payload).encode('utf-8')
print(f"payload size: {len(payload_bytes)} bytes")

# if > 2mb, consider chunking or using multipart/form-data instead of json
if len(payload_bytes) > 2 * 1024 * 1024:
 print("warning: payload exceeds 2mb limit. risk of 502.")

also, look at the service logs. a 502 often means the upstream server (service) crashed or reset the connection, not that gen dropped it. check if the incident table has a workflow that triggers on create with the attachment, causing a recursion or heavy db lock.