PATCH /api/v2/conversations/calls/{id}/participants failing 409 when writing attributes

NICE CXone API & Integrations
1

Trying to push custom attributes back to Genesys Cloud from my Kotlin Android app during an active voice call. The PATCH /api/v2/conversations/calls/{id}/participants/{participantId} call keeps returning a 409 Conflict with version mismatch errors even though I’m pulling the latest version header from the WebSocket event payload. The JSON body looks correct but the server rejects the update immediately.

2

That 409 is almost always a version mismatch in the header. You’re pulling the version from the WebSocket event, but by the time your Kotlin app processes it and fires the PATCH, the server might have already updated that participant object for another reason (like a status change). The If-Match header needs to match the exact current version on the server at the moment of the request.

Try fetching the latest participant state via the API right before you patch, or handle the 409 by catching it, fetching the current object, merging your attributes, and retrying. Here’s a quick retry logic snippet:

try {
 apiClient.patchConversationCallParticipant(conversationId, participantId, body, headers)
} catch (e: ApiException) {
 if (e.code == 409) {
 // Fetch latest version and retry
 val current = apiClient.getConversationCallParticipant(conversationId, participantId)
 headers["If-Match"] = current.version.toString()
 apiClient.patchConversationCallParticipant(conversationId, participantId, body, headers)
 }
}

Make sure you’re not sending an old version number in the If-Match header. It’s tricky with real-time data.