Participant attributes not persisting via PATCH /api/v2/conversations/voice/participants

I’m building a custom agent desktop extension using the Genesys Cloud Embeddable Client App SDK. We need to read and write participant attributes from an external CRM system during a live voice call. Reading works fine, but writing is failing silently or not persisting.

Here’s the flow:

1. Agent clicks a button in our custom UI.
2. We fetch the current conversation and participant IDs.
3. We call the PATCH endpoint to update the participant’s attributes object.

The code looks like this:

const updateAttributes = async (conversationId: string, participantId: string) => {
 const token = await platformClient.auth.getAccessToken();
 const url = `https://{{domain}}.mygen.com/api/v2/conversations/voice/conversations/${conversationId}/participants/${participantId}`;
 
 const payload = {
 attributes: {
 ...currentAttributes,
 'crm.lastUpdate': Date.now()
 }
 };

 const response = await fetch(url, {
 method: 'PATCH',
 headers: {
 'Content-Type': 'application/json',
 'Authorization': `Bearer ${token}`
 },
 body: JSON.stringify(payload)
 });

 return response;
};

The response comes back as 204 No Content. No errors. But when I check the conversation in the Admin UI or query the API again, the attribute isn’t there. Sometimes it shows up briefly then disappears. Other times it never appears.

I’ve tried:

• Using the platformClient.conversations.updateConversationParticipant SDK method directly.
• Adding ifMatch header with the ETag from the GET response.
• Checking permissions on the OAuth client (it has conversations:view and conversations:write).
• Verifying the attributes object is serializable JSON.

Is there a specific way attributes need to be structured? Or is PATCH not the right verb for this? The docs are vague on attribute persistence behavior.

You’re likely hitting the issue where the PATCH payload doesn’t include the full current state of the participant object, or the API versioning is off. The Voice participant endpoint is strict about this.

Try using the SDK instead of raw HTTP if you can, but if you must use curl or direct API calls, ensure you’re sending the complete updated participant object, not just the attributes diff. Genesys Cloud often requires the full resource for PATCH operations on participants to prevent race conditions.

Here’s a working example using the Python SDK, which handles the object construction for you:

from genesyscloud.platform.client import PlatformClient

# Initialize client
platform_client = PlatformClient.create_with_client_credentials(
 environment="mypurecloud.com",
 client_id="your_client_id",
 client_secret="your_client_secret"
)

conversation_id = "your_conversation_id"
participant_id = "your_participant_id"

# Get the current participant first to ensure you have the full object
current_participant = platform_client.conversations_api.get_conversations_voice_participant(
 conversation_id=conversation_id,
 participant_id=participant_id
).body

# Update the attributes
current_participant.attributes["custom_key"] = "custom_value"

# Patch the full participant object back
platform_client.conversations_api.patch_conversations_voice_participant(
 conversation_id=conversation_id,
 participant_id=participant_id,
 body=current_participant
)

If you’re doing this via raw API, the JSON body must look like this:

{
 "id": "participant_id_here",
 "name": "Agent Name",
 "address": "+1234567890",
 "externalContactId": "optional",
 "attributes": {
 "custom_key": "custom_value"
 },
 "wrapUpCode": null,
 "monitoringState": "monitored",
 "skillEval": false
}

Missing fields like address or externalContactId can cause the update to fail silently or revert. Also check your OAuth scopes. You need conversation:write and conversation:read.

One other thing - if you’re doing this from an embedded client, make sure the token you’re using has the right permissions. The embeddable client tokens sometimes have restricted scopes depending on how you generated them.

Skip the full object merge. That’s a headache waiting to happen. Just use the SDK’s updateConversationVoiceParticipant method. It handles the partial update logic for you.

const body = new PlatformClient.Participant({ attributes: { newKey: 'val' } });
client.ConversationsApi.updateConversationVoiceParticipant(convId, partId, body);

Way cleaner.