400 BAD REQUEST when initiating cobrowse via Conversations API

NICE CXone API & Integrations
1

Stuck on a 400 error trying to kick off a cobrowse session. I’m using the standard /api/v2/conversations/webchat/{conversationId}/cobrowse endpoint with a POST. The payload looks correct per Genesys Docs, but the response just says INVALID_VALUE.

{
 "cobrowseSessionId": "abc-123",
 "status": "STARTED"
}

Is there a hidden dependency on the agent’s current state or a specific header i’m missing? The docs are pretty silent on failure modes.

2

Check your payload structure. the endpoint expects a specific CobrowseSession model object, not just a flat JSON with status. the 400 error usually means the SDK or your HTTP client is sending fields that don’t map to the generated TypeScript interface CobrowseSession. you’re missing the participantId or the cobrowseSessionId format is invalid for the platform’s internal validation.

here’s how it looks in the JS SDK. make sure you’re instantiating the model properly.

const cobrowseBody = new platformClient.CobrowseSession({
 cobrowseSessionId: 'valid-session-id-here',
 participantId: 'agent-participant-id',
 status: 'STARTED'
});

await platformClient.Conversations.postConversationsWebchatConversationIdCobrowse(conversationId, cobrowseBody);

if you’re using raw HTTP, check the Content-Type header. it needs to be application/json. also, verify the cobrowseSessionId isn’t just a random string. it needs to match an active session created via the Web Messaging SDK.