> ## Documentation Index > Fetch the complete documentation index at: https://chatbase.co/docs/llms.txt > Use this file to discover all available pages before exploring further. # Add a message to a ticket > Posts an agent reply to a ticket on behalf of a team member. Delivery to the customer is asynchronous; a 201 confirms the reply was recorded, not delivered. Posting a reply may transition the ticket status, matching dashboard behavior. ## OpenAPI ````yaml /api-v2-openapi.json post /agents/{agentId}/helpdesk/tickets/{ticketNumber}/messages openapi: 3.1.0 info: title: Chatbase API v2 version: 2.0.0 description: >- Chatbase API v2 - A robust, structured API for managing agents, conversations, and the helpdesk. servers: - url: https://www.chatbase.co/api/v2 description: Chatbase API v2 security: [] paths: /agents/{agentId}/helpdesk/tickets/{ticketNumber}/messages: post: tags: - Helpdesk summary: Add a message to a ticket description: >- Posts an agent reply to a ticket on behalf of a team member. Delivery to the customer is asynchronous; a 201 confirms the reply was recorded, not delivered. Posting a reply may transition the ticket status, matching dashboard behavior. operationId: createTicketMessage parameters: - schema: type: string minLength: 1 description: The agent ID example: 5QHA6VB-DIAbBhxwqxfdi required: true description: The agent ID name: agentId in: path - schema: type: integer exclusiveMinimum: 0 maximum: 2147483647 description: The ticket number example: 123 required: true description: The ticket number name: ticketNumber in: path requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/CreateTicketMessageBody' responses: '201': description: The created message content: application/json: schema: $ref: '#/components/schemas/CreatedTicketMessage' '400': description: >- The request body failed schema validation. Inspect the `details` object in the error response for field-level errors. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: VALIDATION_INVALID_BODY message: Invalid request '401': description: >- No Authorization header present. Provide a valid API key as a Bearer token in the Authorization header: `Authorization: Bearer `. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: AUTH_MISSING_API_KEY message: Authentication required '403': description: >- Your current plan does not include API access. Upgrade to the Basic plan or higher to use the API. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: SUBSCRIPTION_API_RESTRICTED_PLAN message: A Basic plan or higher is required to access the API '404': description: >- No ticket matches the provided ticket number for this agent. Verify the ticket number in the request path. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: TICKET_NOT_FOUND message: The requested ticket could not be found '409': description: >- The ticket cannot take a human reply: its conversation is not taken over, the ticket was merged into another ticket, or the ticket is closed. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' examples: CONVERSATION_NOT_TAKEN_OVER: summary: >- This ticket is linked to a live conversation that has not been taken over from the AI agent, so a human reply cannot be posted. Take over the conversation from the dashboard first. value: error: code: CONVERSATION_NOT_TAKEN_OVER message: The linked conversation is not taken over TICKET_MERGED: summary: >- This ticket was merged into another ticket. It no longer accepts replies, and its status can only move between closed statuses. Continue on the ticket it was merged into. value: error: code: TICKET_MERGED message: The ticket was merged into another ticket TICKET_CLOSED: summary: >- This ticket is closed or cancelled and its conversation was handed over from the AI agent, so it accepts no replies and cannot be reopened. It can still move between closed and cancelled statuses. To keep talking to the customer, reply on the conversation's open ticket, or take over the conversation from the dashboard to open a new one. value: error: code: TICKET_CLOSED message: >- The ticket is closed and cannot be reopened or replied to '422': description: >- The authorId or authorEmail does not resolve to a member of your account. Authors must be existing team members. Also returned with code `MESSAGE_CONTENT_NOT_RENDERABLE` when the message body renders to empty HTML. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: TEAM_MEMBER_NOT_FOUND message: No team member matches the provided author '429': description: >- Rate limit exceeded. Check the `X-RateLimit-Reset` response header for the Unix epoch seconds when the limit resets. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: RATE_LIMIT_TOO_MANY_REQUESTS message: Too many requests, please try again later '500': description: >- An unhandled server error occurred. If the issue persists, contact support with the `x-request-id` response header value for debugging. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: INTERNAL_SERVER_ERROR message: Something went wrong, please try again '503': description: >- Chatbase is undergoing scheduled maintenance and the API is temporarily rejecting requests. This is transient; retry after a short delay. Requests are rejected before any data is read or written, so no partial changes are applied. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: SERVICE_UNDER_MAINTENANCE message: >- The API is temporarily unavailable for scheduled maintenance, please try again later security: - bearerAuth: [] components: schemas: CreateTicketMessageBody: type: object properties: type: type: string enum: - reply description: >- Message type. Only `reply` (customer-visible, delivered to the customer) is supported. example: reply content: type: string minLength: 1 maxLength: 10000 description: >- Message body as GitHub-flavored Markdown. Plain text is valid markdown; single newlines are kept as line breaks. Raw inline HTML is stripped. Limited to 10,000 characters after trimming. example: Thanks for reaching out. This is **fixed** now. authorId: type: string format: uuid description: >- Platform user id of the team member the reply is attributed to. Provide exactly one of authorId / authorEmail. authorEmail: type: string format: email description: >- Email of the team member the reply is attributed to (case-insensitive). Provide exactly one of authorId / authorEmail. example: sam@example.com required: - type - content CreatedTicketMessage: type: object properties: id: type: string description: Message id type: type: string enum: - reply description: Message type example: reply sender: allOf: - $ref: '#/components/schemas/MessageSender' - description: The team member the reply is attributed to content: type: string description: Rendered, sanitized HTML body contentText: type: string description: The raw markdown body as submitted createdAt: type: string description: ISO 8601 creation timestamp example: '2026-07-29T09:00:00.000Z' required: - id - type - sender - content - contentText - createdAt ErrorResponse: type: object properties: error: type: object properties: code: type: string description: Machine-readable error code message: type: string description: Human-readable error message details: type: object additionalProperties: type: string description: Field-level validation errors required: - code - message required: - error MessageSender: type: - object - 'null' properties: type: type: string enum: - customer - agent - system description: Who sent the message example: customer id: type: - string - 'null' description: 'Sender id: a platform user id for agents, a contact id for customers' name: type: - string - 'null' description: Sender name email: type: - string - 'null' description: Sender email required: - type - id - name - email description: Null on `event` messages securitySchemes: bearerAuth: type: http scheme: bearer description: API key from your account settings ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.