Open Messaging API: Quick Reply payload structure causing 400 error

Does anyone know the correct JSON schema for sending structured quick replies via the Genesys Cloud Open Messaging API?

I am attempting to push a message with quick replies to an active guest session using the POST /api/v2/conversations/messaging/contacts/{contactId}/messages endpoint. I have verified the OAuth token is valid and the contact ID is correct. However, the request consistently fails with a 400 Bad Request.

Here is the payload I am sending:

{
 "type": "quick_reply",
 "quick_replies": [
 {
 "title": "Yes",
 "payload": "CONFIRM_YES"
 },
 {
 "title": "No",
 "payload": "CONFIRM_NO"
 }
 ]
}

The API returns this error:

“message”: “Invalid request body. The ‘quick_replies’ array items must contain a valid ‘value’ field instead of ‘payload’.”

I have checked the documentation for the Open Messaging API, but it seems ambiguous regarding whether we should use payload (common in other platforms) or value. I tried swapping payload to value, but the error persists. Is there a specific wrapper object required for the quick replies in Genesys Cloud? I am debugging this from Sydney and have tested with both Python requests and Postman.

Your payload structure is wrong because you’re treating quickReplies as a top-level field. Nest it under messageActions like this:

{
 "messageActions": [
 {
 "type": "quickReply",
 "title": "Select Option",
 "options": [
 { "value": "opt1", "label": "Option 1" },
 { "value": "opt2", "label": "Option 2" }
 ]
 }
 ]
}

See the schema here: https://developer.genesys.cloud/api/rest/v2/conversations/messaging/contacts/{contactId}/messages

The documentation actually says messageActions is the correct wrapper.

• Confirm the type is strictly quickReply.
• Validate options array structure matches the schema.
• Check for trailing commas in JSON.

My SvelteKit proxy hit this exact 400 until I fixed the nesting.

This is actually a known issue… while nesting under messageActions is correct, the Open Messaging API is strict about the options payload. You must include description if your channel supports it, otherwise it might reject silently or fail validation. Here is the safe Deno fetch pattern:

const res = await fetch(url, {
 method: "POST",
 body: JSON.stringify({
 messageActions: [{ type: "quickReply", title: "Pick", options: [{ value: "1", label: "A" }] }]
 })
});

You need to ensure the messageActions array is correctly serialized when constructing the request body for POST /api/v2/conversations/messaging/contacts/{contactId}/messages. While the suggestion above correctly identifies the nesting structure, I have encountered strict validation failures when the options sub-object lacks explicit type hints or when the JSON serialization omits null fields that the schema expects.

In my Rust service using reqwest and serde, I define the payload structures explicitly to avoid any ambiguity during serialization. This ensures that the type field is strictly quickReply and that each option contains both label and value. Here is the robust Rust implementation pattern I use to construct this payload:

use serde::{Serialize, Deserialize};

#[derive(Serialize, Deserialize)]
struct QuickReplyOption {
 label: String,
 value: String,
}

#[derive(Serialize, Deserialize)]
struct MessageAction {
 #[serde(rename = "type")]
 action_type: String,
 title: String,
 options: Vec<QuickReplyOption>,
}

#[derive(Serialize, Deserialize)]
struct MessagePayload {
 message_actions: Vec<MessageAction>,
}

fn build_quick_reply_payload() -> MessagePayload {
 MessagePayload {
 message_actions: vec![MessageAction {
 action_type: "quickReply".to_string(),
 title: "Select Option".to_string(),
 options: vec![
 QuickReplyOption { label: "Option 1".to_string(), value: "opt1".to_string() },
 QuickReplyOption { label: "Option 2".to_string(), value: "opt2".to_string() },
 ],
 }],
 }
}

Ensure your HTTP client sends the Content-Type: application/json header. The Genesys Cloud API is strict about this. If you are still seeing a 400 error, validate that the contactId belongs to an active messaging session and that the OAuth token includes the messaging:contact scope. I have found that missing scopes often result in a 403, but malformed JSON with missing required fields like label in the options array will consistently trigger a 400. Double-check your JSON output before sending.