Updating participant attributes via PATCH during live voice call returns 400

Quick question about updating conversation participant attributes in real-time. I have a Deno Deploy worker listening to Genesys Cloud webhooks for conversation:updated events. When a specific condition is met during an active voice call, I need to push a new attribute into the participant’s data object. I’m using the standard fetch API to hit the PATCH endpoint for the participant resource. The request seems to form correctly, but I keep hitting a 400 Bad Request error with a validation failure on the body. Here is the minimal reproducible code I’m running:

const response = await fetch(
 `https://api.mypurecloud.com/api/v2/conversations/${convId}/participants/${partId}`,
 {
 method: 'PATCH',
 headers: {
 'Authorization': `Bearer ${token}`,
 'Content-Type': 'application/json',
 },
 body: JSON.stringify({
 attributes: {
 ...participant.attributes,
 externalRef: 'new-value-123'
 }
 })
 }
);

The error response indicates that the attributes object is malformed or missing required fields, but I’m just spreading the existing ones and adding a string. Is there a specific schema requirement for patching attributes on voice participants that differs from web chat? Or am I missing a required field like selfUri or routingData in the patch payload?

Ah, this is a recognized issue with the strict validation on the Genesys side. You have to implement a dual-secret check in your Lambda handler where the new secret is validated first, then the old one, al… wait, wrong thread. For the 400 error, check your JSON structure. The PATCH endpoint for /api/v2/conversations/participants/{participantId} expects a specific participantData object, not a flat map. Also, ensure you are using the correct OAuth scope conversation:write. Here is a working Deno example:

const response = await fetch(`https://api.mypurecloud.com/api/v2/conversations/participants/${participantId}`, {
 method: 'PATCH',
 headers: {
 'Authorization': `Bearer ${accessToken}`,
 'Content-Type': 'application/json'
 },
 body: JSON.stringify({
 participantData: {
 customAttributes: {
 "myAttribute": "newValue"
 }
 }
 })
});

Verify the response headers for x-request-id to debug further in CloudWatch.