Message Read Events Fail with 409 Error When Supervisor Monitors Chat

[nazha1986]

Message read events (application/vnd.amazonaws.connect.event.message.read) fail with 409 Conflict when a SUPERVISOR is monitoring the chat session.

Error Response:

{
  "message": "Operation can not be performed due to the state of the contact."
}

🔍 Environment

• Service: Amazon Connect Participant API
• API Endpoint: https://participant.connect.[region].amazonaws.com/participant/event
• Client: Custom web application
• Confirmed in: Official Amazon Connect chat widget (production)

📋 Reproduction Steps

1. Start chat session (CUSTOMER ↔ AGENT)
2. Send read event → ✅ Works (200 OK)
3. SUPERVISOR joins chat (monitoring/barge-in)
4. Send read event → ❌ Fails (409 Conflict)

💻 Request Details

Request:

POST https://participant.connect.[region].amazonaws.com/participant/event

Headers:
  Content-Type: application/json
  X-Amz-Bearer: 

Body:
{
  "ContentType": "application/vnd.amazonaws.connect.event.message.read",
  "Content": "{\"messageId\":\"xxx-xxx-xxx\"}"
}

Response (with supervisor):

409 Conflict
{
  "message": "Operation can not be performed due to the state of the contact."
}