Proactive Web Messaging Notification via API failing with 400 Bad Request

• Environment: Node.js 18, Express 4.18
• SDK: @genesyscloud/purecloud-platform-client-v2 (v1.12.0)
• Region: eu-west-1 (Paris)
• Web Messaging Channel ID: 8a7b6c5d-1e2f-3a4b-5c6d-7e8f9a0b1c2d

Why does this setting cause the API to reject the proactive message payload? I am building a Teams bot that syncs agent presence with Genesys Cloud. When an agent becomes available in GC, I want to trigger a proactive web message to a customer who had an active session in the last 24 hours. I am using the conversations.messages.create endpoint to inject a message into an existing conversation, but it fails with a 400 Bad Request.

I have successfully retrieved the conversation ID from the analytics endpoint and verified the guest token is still valid within the session timeout. Here is the code snippet I am using to send the message:

const { createMessage } = require('@genesyscloud/purecloud-platform-client-v2');

async function sendProactiveMessage(conversationId, guestToken) {
 const messagePayload = {
 type: 'message',
 text: 'Hello, an agent is now available.',
 from: {
 id: 'system-bot-id', // Verified ID
 name: 'System'
 },
 to: {
 id: guestToken,
 name: 'Guest'
 },
 conversationId: conversationId
 };

 try {
 const response = await createMessage({
 body: messagePayload,
 conversationId: conversationId,
 xGenesysAuth: getToken() // Valid OAuth2 token with conversation:write scope
 });
 console.log('Message sent:', response);
 } catch (error) {
 console.error('Error:', error.response.data);
 }
}

The error response is:

{
 "errorCode": "invalid.request",
 "message": "Invalid message payload. Type must be 'message' or 'event'."
}

I have confirmed the type is ‘message’. The conversation is of type ‘webMessaging’. Is there a specific header or payload structure required for proactive messages that differs from standard agent replies? The standard reply flow works fine, but injecting a message from the API side for a closed or idle session seems to hit this wall. Any insights on the exact JSON schema required for this specific use case?

Depends on your setup, but generally the payload structure for proactive messaging differs significantly from standard outbound APIs. The 400 error usually indicates a mismatch in the message object schema or missing channel-specific identifiers.

Ensure your Node.js request includes the correct OAuth scope (messaging:send).

Take a look at at the exact JSON structure required for the message object in the proactive send API. The 400 error is almost certainly due to a schema mismatch, specifically regarding the type field or missing to identifiers.

I hit this same wall last week while testing Python snippets for outbound web messaging. The SDK documentation is vague on the strict requirements for proactive channels compared to standard outbound. Here is the minimal working payload that bypassed the 400 for me:

from purecloudplatformclientv2 import WebMessagingApi, WebMessagingSendRequest

# Initialize API
client = PureCloudPlatformClientV2()
client.login(username, password)
wm_api = WebMessagingApi(client)

# Construct the request body
# Note: 'type' must be 'proactive' and 'channelId' must match your Web Messaging channel
request_body = {
 "type": "proactive",
 "channelId": "8a7b6c5d-1e2f-3a4b-5c6d-7e8f9a0b1c2d",
 "to": {
 "type": "web",
 "id": "session-id-from-client-js" # This comes from the web client SDK
 },
 "from": {
 "type": "agent",
 "id": "agent-id-or-user-id" # Must be an authenticated user ID
 },
 "body": {
 "contentType": "text/plain",
 "content": "Hello from proactive message"
 }
}

try:
 response = wm_api.post_webmessaging_send(body=request_body)
 print(f"Message sent successfully: {response}")
except Exception as e:
 print(f"Error: {e}")

Key points to verify:

• The to.id must be the session ID generated by the Genesys Cloud Web Messaging client on the customer’s browser. You cannot fake this.
• The from.id must be a valid user ID associated with an agent or bot that has permissions to send messages on that channel.
• Ensure your OAuth token includes the webmessaging:send scope.

The Node.js SDK maps this to WebMessagingSendRequest. Check if your to object is missing the type: 'web' field. That was my blocker. Also, verify the region endpoint matches https://api.euw2.pure.cloud for eu-west-1.

Check your JSON payload structure and ensure the to field contains a valid web messaging participant ID or channel token, as the 400 error often stems from schema validation failures in the message object. Building on the schema discussion above, I have found that the Go SDK’s MessageSend struct requires explicit initialization of the To and Content fields to avoid nil pointer dereferences or serialization mismatches. When triggering proactive messages from a high-throughput Go service, I recommend constructing the payload manually to ensure strict compliance with the application/json content type and correct field typing. Here is a working example using the platformClient to send a proactive web message:

import (
 "context"
 "github.com/myBot/go-purecloud/platformclientv2"
)

func sendProactiveWebMessage(ctx context.Context, channelID string, recipientID string, messageText string) error {
 // Initialize the API client
 apiClient := platformclientv2.NewConversationApi()
 
 // Construct the message body
 requestBody := platformclientv2.MessageSend{
 To: &[]platformclientv2.MessageAddress{
 {
 Address: &recipientID,
 Type: platformclientv2.StringPointer("webchat"), // Ensure correct type
 },
 },
 Content: &platformclientv2.MessageContent{
 Type: platformclientv2.StringPointer("text"),
 Text: &messageText,
 },
 }

 // Execute the send request
 _, _, err := apiClient.PostConversationMessageSend(ctx, channelID, requestBody)
 if err != nil {
 return fmt.Errorf("failed to send proactive message: %w", err)
 }
 return nil
}

Verify that the channelID corresponds to an active web messaging channel and that your OAuth token includes the conversation:send scope. If the error persists, inspect the raw HTTP response body for specific validation errors, as the SDK may mask detailed schema mismatch messages.