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

# API changelog

> Partner API version releases

<Update
  label="2026-10-13"
  description="Breaking changes"
  tags={["Breaking", "Customer Links"]}
  rss={{
date: "2026-10-13",
title: "API version 2026-10-13",
description: "Linking a customer who is already linked to a different partner customer ID now returns 409 CUSTOMER_ALREADY_LINKED. Earlier versions return 200 with the existing link. Use PATCH on the customer link to change the ID."
}}
>
  * **Breaking:** [`POST /v2/customers/{customer_id}/link`](https://docs.imprint.co/api-reference/customer-links/link-an-imprint-customer-and-partner-customer-accounts)
    returns `409 CUSTOMER_ALREADY_LINKED`, with the current link in `error.existing_link`, when the
    customer is already linked to a different `partner_customer_id`. Earlier versions return `200` with
    the existing link. To change the linked ID, use
    [`PATCH /v2/customers/{customer_id}/link`](https://docs.imprint.co/api-reference/customer-links/update-the-partner-customer-id-of-a-customer-link).
    A request with the same `partner_customer_id` returns `200` on every version.
</Update>


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