Open Messaging API POST /api/v2/conversations/messages failing on structured content payload

NICE CXone API & Integrations
1

I’m hitting a brick wall trying to send structured messages (specifically quick replies) via the Open Messaging API. I need this to work so I can inject trace context into the message payload for my OpenTelemetry pipeline.

The POST to /api/v2/conversations/messages returns a 400 Bad Request. The body is minimal:

{
 "content": {
 "type": "application/vnd.genesys.messaging.card+json",
 "card": {
 "type": "quick-reply",
 "text": "Select an option",
 "buttons": [
 { "type": "action", "title": "Yes", "payload": "yes" },
 { "type": "action", "title": "No", "payload": "no" }
 ]
 }
 }
}

I’ve verified the conversation ID is valid and the token has messaging:write scope. The error message just says Invalid content type or structure. I’ve tried swapping application/vnd.genesys.messaging.card+json for application/json but that throws a different validation error about missing card properties.

Is there a specific schema requirement for the buttons array that I’m missing? The docs are vague on the exact payload structure for quick replies in this endpoint.

2

The type field in your JSON is wrong. You’re using application/vnd.genesys.messaging.card+json but the API expects application/vnd.genesys.messaging.card+json only for specific card types, and even then, the structure inside card is off. For quick replies, the standard is simpler.

The docs say: “Quick reply cards must contain a title and an array of buttons.” You’re missing the buttons. Also, check your to address. It has to be a valid address in the conversation.

Here’s what actually works in C# with the SDK:

var message = new MessageContent();
message.Type = "application/vnd.genesys.messaging.card+json";
message.Card = new Card();
message.Card.Type = "quick-reply";
message.Card.Title = "Select an option";
message.Card.Buttons = new List<Button>
{
 new Button { Title = "Option 1", Value = "val1" },
 new Button { Title = "Option 2", Value = "val2" }
};

var postMessage = new PostConversationMessageRequest
{
 To = new Address { Address = "user@genesys.cloud", Type = "email" }, // or sms, depending on your channel
 Content = message
};

try 
{
 var result = await _messagingClient.PostConversationMessagesAsync(conversationId, postMessage);
}
catch (ApiException ex)
{
 Console.WriteLine(ex.Response);
}

If you’re hitting 400, print the ex.Response body. Genesys usually tells you exactly which field is invalid. It’s rarely the trace context stuff causing the 400 at this stage. That happens later in the pipeline.

3

You’re overcomplicating the payload. Just use the standard text type with quick reply actions. It’s cleaner and doesn’t require the card wrapper.

{
 "content": {
 "type": "text",
 "text": "Pick an option:",
 "actions": [
 {
 "type": "button",
 "label": "Option 1",
 "value": "opt_1"
 }
 ]
 }
}