# Update cart item by cart ID

Updates an existing cart item or creates the one in the cart.

Endpoint: PUT /v2/project/{project_id}/cart/{cart_id}/item/{item_sku}
Version: 2.0.0
Security: AuthForCart

## Path parameters:

  - `project_id` (integer, required)
    Project ID. You can find this parameter in your Publisher Account next to the name of the project.
    Example: 44056

  - `cart_id` (string, required)
    Cart ID.
    Example: "custom_id"

  - `item_sku` (string, required)
    Item SKU.
    Example: "booster_mega_1"

## Request fields (application/json):

  - `quantity` (number)
    Item quantity.

## Response 404 fields (application/json):

  - `statusCode` (integer)
    Example: 404

  - `errorCode` (integer)
    Example: 4001

  - `errorMessage` (string)
    Example: "[0401-4001]: Item with Project Id = 44056 and Sku = booster_mega_12222 not found"

## Response 422 fields (application/json):

  - `statusCode` (integer)
    Example: 422

  - `errorMessage` (string)
    Example: "Item quantity must be non-negative integer."

  - `errorCode` (integer)
    Example: 1102


## Response 204 fields