---
title: "Update merchant default language"
method: PATCH
path: "/v2/localization/merchants/{merchant_id}/language"
tags: ["Localization"]
---

# Update merchant default language

`PATCH /v2/localization/merchants/{merchant_id}/language`

Updates the default language for a merchant (program).

## Path parameters

- `merchant_id` string, required

## Headers

- `authorization` string, nullable

## Request body

- LanguagePreferenceUpdate — Request model for updating language preference.
  - `languageCode` string, required — Language code (e.g., 'en-US', 'es-ES')

## Response `200`

Successful Response

- MerchantLanguageUpdateResponse — Response model for merchant language update.
  - `id` string, required
  - `sid` string, required
  - `defaultLanguage` string, nullable, required
  - `languagePreference` object, nullable — Language preference info

## Other responses

- `422` — Validation Error

---

[API](https://skmtc.net/loyalty/apis/loyaltydog.md) · [All operations](https://skmtc.net/loyalty/apis/loyaltydog/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/loyalty/loyaltydog/versions/42b7b22af2b6/schema)