> ## Documentation Index
> Fetch the complete documentation index at: https://www.mill.fyi/llms.txt
> Use this file to discover all available pages before exploring further.

# Update a board

> Edit board settings. Prefixes must be unique; changing one renames existing task identifiers while preserving task numbers and links. Send the current version to protect concurrent edits.

Write access: a member/administrator with a write-enabled credential, or an authorized signed-in user.

Edit board settings. Prefixes must be unique; changing one renames existing task identifiers while preserving task numbers and links. Send the current version to protect concurrent edits.

A prefix change atomically renames existing task identifiers while preserving task numbers and UUID links. Existing task versions increase. Duplicate prefixes return 409 `BOARD_PREFIX_TAKEN`; stale versions conflict. Omitted fields remain unchanged.

MCP clients can use [`update_board`](https://www.mill.fyi/mcp-reference/update_board) for this operation.

[Request conventions](https://www.mill.fyi/api-reference/overview.md) · [API keys](https://www.mill.fyi/api-keys.md) · [MCP connections](https://www.mill.fyi/mcp-connections.md)


## OpenAPI

````yaml api-reference/openapi.json PATCH /api/boards/{boardId}
openapi: 3.1.0
info:
  title: Mill HTTP API
  version: 1.0.6
  description: >-
    All registered task-board, account, OAuth, MCP transport and health
    operations. MCP tool schemas come from runtime validators; account
    operations follow their server handlers. Example data is fictional.
    Generation imports routes without issuing requests or connecting to a
    database.
servers:
  - url: https://mill-api.example.com
security: []
paths:
  /api/boards/{boardId}:
    patch:
      tags:
        - Boards
      summary: Update a board
      description: >-
        Edit board settings. Prefixes must be unique; changing one renames
        existing task identifiers while preserving task numbers and links. Send
        the current version to protect concurrent edits.


        A prefix change atomically renames existing task identifiers while
        preserving task numbers and UUID links. Existing task versions increase.
        Duplicate prefixes return 409 `BOARD_PREFIX_TAKEN`; stale versions
        conflict. Omitted fields remain unchanged.


        Write access: a member/administrator with a write-enabled credential, or
        an authorized signed-in user.
      operationId: patch_api_boards_by_boardId
      parameters:
        - name: boardId
          in: path
          required: true
          schema:
            type: string
            format: uuid
          description: >-
            The boardId from the corresponding list, record or authorization
            response.
        - name: Origin
          in: header
          required: false
          schema:
            type: string
            format: uri
          description: >-
            The exact configured Mill UI origin. Required for browser mutations
            carrying session cookies.
        - name: Idempotency-Key
          in: header
          required: false
          schema:
            type: string
            minLength: 8
            maxLength: 128
            pattern: ^[A-Za-z0-9._:-]+$
          description: >-
            Reuse the same key and exact request bytes for retries of one
            logical mutation; different content conflicts.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties:
                version:
                  type: integer
                  exclusiveMinimum: 0
                  maximum: 9007199254740991
                name:
                  type: string
                  minLength: 1
                  maxLength: 100
                description:
                  type: string
                  maxLength: 10000
                prefix:
                  type: string
                  pattern: ^[A-Z][A-Z0-9]{1,9}$
              required:
                - version
              additionalProperties: false
            example:
              version: 1
              prefix: OPS
      responses:
        '200':
          description: >-
            Successful response. Examples are illustrative; field values vary by
            record.
          content:
            application/json:
              schema:
                type: object
                properties:
                  board:
                    type: object
                    properties:
                      id:
                        type: string
                      workspaceId:
                        type: string
                      name:
                        type: string
                      prefix:
                        type: string
                      description:
                        type: string
                      version:
                        type: integer
                      nextNumber:
                        type: integer
                      createdAt:
                        type: string
                      updatedAt:
                        type: string
                      createdByUserId:
                        type: string
                      createdByName:
                        type: string
                      createdByKind:
                        type: string
                      lastActivityAt:
                        type: string
                    additionalProperties: true
                additionalProperties: true
                description: >-
                  Illustrative response shape. Fields can be absent in alternate
                  successful flows; see the operation description and example.
              example:
                board:
                  id: 11111111-1111-4111-8111-111111111111
                  workspaceId: 55555555-5555-4555-8555-555555555555
                  name: Engineering
                  prefix: OPS
                  description: Track delivery and reliability.
                  version: 2
                  nextNumber: 2
                  createdAt: '2027-01-18T09:30:00.000Z'
                  updatedAt: '2027-01-18T09:30:00.000Z'
                  createdByUserId: 66666666-6666-4666-8666-666666666666
                  createdByName: Alex Morgan
                  createdByKind: human
                  lastActivityAt: '2027-01-18T09:30:00.000Z'
        default:
          description: >-
            Request failure. Inspect code, message and requestId; respect
            Retry-After on HTTP 429.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
      security:
        - bearerAuth: []
        - sessionCookie: []
components:
  schemas:
    Error:
      type: object
      required:
        - error
      properties:
        error:
          type: object
          required:
            - code
            - message
            - requestId
          properties:
            code:
              type: string
            message:
              type: string
            requestId:
              type: string
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      description: Personal or team Mill REST API key
    sessionCookie:
      type: apiKey
      in: cookie
      name: mill_session
      description: >-
        Signed-in human browser session; mutation requests also need the exact
        UI Origin

````

This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.