Update Line Item
Updates a *Checkout Line Item*. Updates an existing, single line item in the cart.
If a variant needs to be changed or updated, the product will need to be removed and re-added to the cart with the correct variants using the [Add Cart Line Items](/developer/api-reference/rest/storefront/carts/cart-items/add-cart-line-item) endpoint or the [GraphQL Storefront API](/developer/docs/storefront/guides/graphql-storefront-api/overview).
> #### Notes
> * Substitute your storefront domain for `yourstore.example.com`.
> * The Send a Test Request feature is not currently supported for this endpoint.
> * Please note that this API endpoint is not concurrent safe, meaning multiple simultaneous requests could result in unexpected and inconsistent results.
> * This endpoint requires using Stencil CLI, a local session, and a CSRF token to work.