Sending proactive notifications to a customer who previously had a web messaging session

Hey everyone, I’ve run into a really strange issue with the Genesys Cloud Web Messaging API when trying to send a proactive notification to a user who already has a valid session cookie. I am using Laravel with Guzzle to handle the HTTP requests, and everything works fine for new sessions, but I get a 409 Conflict when trying to initiate a new message on an existing conversation ID.

The flow is pretty standard. I store the webchatSessionId and contactId in my database when the user first connects. Later, I trigger a scheduled job to send a proactive message. I am using the POST /api/v2/conversations/webchat/messages endpoint. Here is the payload structure I am sending:

{
 "webchatSessionId": "abc123-session-token",
 "contactId": "xyz789-contact-id",
 "from": {
 "id": "my-bot-user-id"
 },
 "text": "Hello, do you need help?"
}

The error response body indicates that the conversation is already active or locked, which makes sense since the user is technically still “connected” from their previous visit, even if they closed the browser tab. I want to push this message into their existing queue or trigger a notification on their device without starting a whole new conversation thread.

Here is what I have tried so far:

• I attempted to use the POST /api/v2/conversations/messaging/contacts/{contactId}/messages endpoint instead, thinking it might be more resilient to session states. However, this requires a different authentication scope and I am getting a 403 Forbidden error, likely because my service account lacks the messaging:contact:write permission. I verified the OAuth token is valid by checking it against the introspect endpoint.
• I tried adding a force flag or some custom header to bypass the conflict, but the Genesys API documentation does not list any such parameters for the webchat messages endpoint. I also checked if there is a way to “reconnect” the session via the API, but I only see WebSocket client-side logic for that, not a RESTful approach.

Is there a specific API call to “ping” an existing webchat session and push a message, or do I need to handle this via the EventBridge integration to trigger a server-sent event? I want to avoid forcing the user into a new conversation context.

Check your payload structure. The 409 Conflict means the server sees an active session for that webchatSessionId and rejects the duplicate initiation request. You must reuse the existing conversationId instead of creating a new one.

If I recall correctly, the 409 Conflict is not a bug but a strict state enforcement by the Web Messaging service. You are likely hitting the endpoint that initiates a new session rather than injecting a message into an existing conversation. The suggestion above is correct, but you need to be precise about which API call to swap.

Here is the correct Laravel/Guzzle implementation to resume an existing session and send a message:

// Use the existing conversationId, not webchatSessionId for the message body
$resumeUrl = "https://api.mypurecloud.com/api/v2/conversations/webchat";
$messagePayload = [
 'from' => [
 'id' => $existingContactId, 
 'type' => 'contact'
 ],
 'text' => 'Proactive notification content...',
 'type' => 'message'
];

try {
 $response = $client->post($resumeUrl, [
 'json' => $messagePayload,
 'headers' => [
 'Authorization' => 'Bearer ' . $accessToken,
 'Content-Type' => 'application/json',
 'X-Genesys-Client-Id' => 'your_client_id',
 'X-Genesys-Client-Version' => '2.0' // Ensure version match
 ]
 ]);
} catch (\GuzzleHttp\Exception\ClientException $e) {
 // Log specific 409 details for debugging session state
 error_log($e->getResponse()->getBody()->getContents());
}

The key is ensuring your webchatSessionId matches the active session in Genesys Cloud’s memory. If that ID has expired or been invalidated by a timeout, you cannot resume. In my Vue dashboard projects, I handle this by checking the WebSocket connection state before attempting the POST. If the client-side session is stale, I force a re-initialization instead of trying to push into a dead conversation. Also, verify you have the webchat:write scope on your OAuth token, as missing scopes often throw confusing 400/409 errors in Guzzle.

It depends, but generally… the 409 is expected behavior when the client attempts to instantiate a new session object while a live webchatSessionId persists in the Genesys Cloud state store. I have traced similar failures in Node.js handlers where the token lacked messaging:conversation:write, causing the API to reject the duplicate initiation attempt as a conflict rather than a permission error. To resolve this, you must stop calling the session creation endpoint and instead route your Laravel Guzzle request to /api/v2/conversations/messaging/{conversationId}/messages. Ensure your OAuth token includes the messaging:conversation:write scope; without it, the server will mask the scope mismatch with a 409. I recommend adding a pre-flight check to validate the session status via GET /api/v2/conversations/messaging/{conversationId} before attempting the POST. This prevents redundant writes and aligns with least-privilege scope design principles. If the session is closed, you can initiate a new one, but for active sessions, strictly reuse the existing conversationId.

My usual workaround is to routing the conflict to an EventBridge rule instead of handling it in the API layer. The 409 means the session is active. Use aws-sdk/client-eventbridge to trigger a Step Function that calls /api/v2/conversations/messaging/{conversationId}/messages. This keeps your Lambda stateless.

const rule = new Rule(this, 'ProactiveMsgRule', {
 eventPattern: { source: ['com.genesys.cloud'] }
});