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

# Set device language/locale

> Sets the device language/locale to the BCP-47 locale in the request body. An optional restart flag applies the change immediately by restarting the Android system framework (open apps are closed) instead of waiting for the next reboot; some devices ignore it.

Include a region subtag — use `de-DE` rather than `de` — since some devices reject language-only locales. Script subtags may be dropped: `zh-Hans-CN` is applied as `zh-CN`.

If the device cannot apply the requested locale, the call fails with a verification error instead of silently keeping the old language.


## OpenAPI

````yaml /api-reference/phones/language.yaml post /devices/{deviceId}/language
openapi: 3.1.0
info:
  title: Language
  version: v1
servers:
  - description: Droidrun Cloud API
    url: https://api.mobilerun.ai/v1
security:
  - bearerAuth: []
paths:
  /devices/{deviceId}/language:
    post:
      tags:
        - Language
      summary: Set device language/locale
      description: >-
        Sets the device language/locale to the BCP-47 locale in the request
        body. An optional restart flag applies the change immediately by
        restarting the Android system framework (open apps are closed) instead
        of waiting for the next reboot; some devices ignore it.
      operationId: set-language
      parameters:
        - in: path
          name: deviceId
          required: true
          schema:
            type: string
        - in: header
          name: X-Device-Display-ID
          schema:
            default: 0
            format: int64
            minimum: 0
            type: integer
      requestBody:
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/SetLanguageArgs'
        required: true
      responses:
        '204':
          description: No Content
        default:
          content:
            application/problem+json:
              schema:
                $ref: '#/components/schemas/ErrorModel'
          description: Error
      x-codeSamples:
        - lang: JavaScript
          source: >-
            import Mobilerun from '@mobilerun/sdk';


            const client = new Mobilerun({
              apiKey: process.env['MOBILERUN_CLOUD_API_KEY'], // This is the default and can be omitted
            });


            await client.devices.language.set('deviceId', { locale:
            'sqf-Kkif-BB' });
        - lang: Python
          source: |-
            import os
            from mobilerun_sdk import Mobilerun

            client = Mobilerun(
                api_key=os.environ.get("MOBILERUN_CLOUD_API_KEY"),  # This is the default and can be omitted
            )
            client.devices.language.set(
                device_id="deviceId",
                locale="sqf-Kkif-BB",
            )
components:
  schemas:
    SetLanguageArgs:
      additionalProperties: false
      properties:
        $schema:
          description: A URL to the JSON Schema for this object.
          examples:
            - https://example.com/schemas/SetLanguageArgs.json
          format: uri
          readOnly: true
          type: string
        locale:
          description: >-
            BCP-47 locale: a 2–3 letter language tag, optionally followed by a
            4-letter script and/or a 2-letter region (e.g. en-US, de-DE, ja-JP,
            zh-Hans-CN).
          pattern: ^[a-z]{2,3}(-[A-Z][a-z]{3})?(-[A-Z]{2})?$
          type: string
        restart:
          description: >-
            Restart the Android system framework so the locale change takes full
            effect immediately; open apps are closed. Without it, the change may
            not fully apply until the next reboot. Some devices ignore this
            flag.
          type: boolean
      required:
        - locale
      type: object
    ErrorModel:
      additionalProperties: false
      properties:
        $schema:
          description: A URL to the JSON Schema for this object.
          examples:
            - https://example.com/schemas/ErrorModel.json
          format: uri
          readOnly: true
          type: string
        detail:
          description: >-
            A human-readable explanation specific to this occurrence of the
            problem.
          examples:
            - Property foo is required but is missing.
          type: string
        errors:
          description: Optional list of individual error details
          items:
            $ref: '#/components/schemas/ErrorDetail'
          type:
            - array
            - 'null'
        instance:
          description: >-
            A URI reference that identifies the specific occurrence of the
            problem.
          examples:
            - https://example.com/error-log/abc123
          format: uri
          type: string
        status:
          description: HTTP status code
          examples:
            - 400
          format: int64
          type: integer
        title:
          description: >-
            A short, human-readable summary of the problem type. This value
            should not change between occurrences of the error.
          examples:
            - Bad Request
          type: string
        type:
          default: about:blank
          description: A URI reference to human-readable documentation for the error.
          examples:
            - https://example.com/errors/example
          format: uri
          type: string
      type: object
    ErrorDetail:
      additionalProperties: false
      properties:
        location:
          description: >-
            Where the error occurred, e.g. 'body.items[3].tags' or
            'path.thing-id'
          type: string
        message:
          description: Error message text
          type: string
        value:
          description: The value at the given location
      type: object
  securitySchemes:
    bearerAuth:
      bearerFormat: Opaque
      description: Bearer token via Authorization header
      scheme: bearer
      type: http

````

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