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

# Updating a checkout session

> Update an existing Dintero Checkout session when the cart items, total amount, or discounts change so the customer always sees the correct order summary.

### Modifying Cart Items, Amounts, and Discounts

When the items of a cart, total amount or discounts are changed on a previously created session, the session must be
updated with the newest changes.

To update the session, first it needs to be locked. Locking the session is done by using the [Checkout Web SDK]. When
the session is locked, updating the session can commence. Documentation for updating the session can be
found [here](/api-reference/session/checkout_session_put)

It's not possible to update a session after it's been completed.

[Checkout Web SDK]: https://github.com/Dintero/Dintero.Checkout.Web.SDK#locking-the-session