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

# Fail Backchannel Authentication Request

> The API prepares JSON that contains an error. The JSON should be used as the response body of the response which is returned to the client from the [backchannel authentication endpoint](https://openid.net/specs/openid-client-initiated-backchannel-authentication-core-1_0.html#auth_backchannel_endpoint).

<Accordion title="Full description" defaultOpen={false}>
  This API is supposed to be called from within the implementation of the [backchannel authentication
  endpoint](https://openid.net/specs/openid-client-initiated-backchannel-authentication-core-1_0.html#auth_backchannel_endpoint)
  of the service in order to generate an error response to the client application.
  The response from `/backchannel/authentication/fails` API has some parameters. Among them, it is
  `action` parameter that the authorization server implementation should check first because it denotes
  the next action that the authorization server implementation should take. According to the value
  of `action`, the authorization server implementation must take the steps described below.

  ## INTERNAL\_SERVER\_ERROR

  When the value of `action` is `INTERNAL_SERVER_ERROR`, it means that (1) the `reason` request parameter
  of the API call was `SERVER_ERROR`, (2) an error occurred on Authlete side, or (3) the request parameters
  of the API call were wrong. In this case, the authorization server implementation should return
  a "500 Internal Server Error" response to the client application. However, in most cases, commercial
  implementations prefer to use other HTTP status code than 5xx.

  ## BAD\_REQUEST

  When the value of `action` is `BAD_REQUEST`, the authorization server implementation should return a
  "400 Bad Request" response to the client application.

  ## FORBIDDEN

  When the value of `action` is `FORBIDDEN`, it means that the `reason` request parameter of the API call
  was `ACCESS_DENIED`. In this case, the backchannel authentication endpoint of the authorization
  server implementation should return a "403 Forbidden" response to the client application.
</Accordion>


## OpenAPI

````yaml https://spec.speakeasy.com/authlete/sdk-workspace/authlete-api-explorer-with-code-samples post /api/{serviceId}/backchannel/authentication/fail
openapi: 3.0.3
info:
  title: Authlete API
  description: ''
  version: 3.0.16
  license:
    name: Apache 2.0
    url: https://www.apache.org/licenses/LICENSE-2.0.html
servers:
  - description: 🇺🇸 US Cluster
    url: https://us.authlete.com
  - description: 🇯🇵 Japan Cluster
    url: https://jp.authlete.com
  - description: 🇪🇺 Europe Cluster
    url: https://eu.authlete.com
  - description: 🇧🇷 Brazil Cluster
    url: https://br.authlete.com
security:
  - bearer: []
tags:
  - name: Service Management
    description: >-
      API endpoints for managing services, including creation, update, and
      deletion of services.
    x-tag-expanded: false
  - name: Client Management
    description: >-
      API endpoints for managing OAuth clients, including creation, update, and
      deletion of clients.
    x-tag-expanded: false
  - name: Authorization Endpoint
    description: API endpoints for implementing OAuth 2.0 Authorization Endpoint.
    x-tag-expanded: false
  - name: Pushed Authorization Endpoint
    description: >-
      API endpoints for implementing OAuth 2.0 Pushed Authorization Requests
      (PAR).
    x-tag-expanded: false
  - name: Token Endpoint
    description: API endpoints for implementing OAuth 2.0 Token Endpoint.
    x-tag-expanded: false
  - name: Token Operations
    description: >-
      API endpoints for various token related operations, including creating,
      revoking and deleting access_tokens with specified scopes.
    x-tag-expanded: false
  - name: Introspection Endpoint
    description: API endpoints for implementing OAuth 2.0 Introspection Endpoint.
    x-tag-expanded: false
  - name: Revocation Endpoint
    description: API endpoint for implementing OAuth 2.0 Revocation Endpoint.
    x-tag-expanded: false
  - name: UserInfo Endpoint
    description: API endpoints for implementing OpenID Connect UserInfo Endpoint.
    x-tag-expanded: false
  - name: JWK Set Endpoint
    description: API endpoints for to generate JSON Web Key Set (JWKS) for a service.
    x-tag-expanded: false
  - name: Discovery Endpoint
    description: API endpoints for implementing OpenID Connect Discovery.
    x-tag-expanded: false
  - name: Configuration Endpoint
    description: API endpoint for accessing configuration settings for a service.
    x-tag-expanded: false
  - name: Dynamic Client Registration
    description: API endpoints for implementing OAuth 2.0 Dynamic Client Registration.
    x-tag-expanded: false
  - name: CIBA
    description: >-
      API endpoints for implementing Client-Initiated Backchannel Authentication
      (CIBA).
    x-tag-expanded: false
  - name: Grant Management Endpoint
    description: >-
      API endpoint for implementing OAuth 2.0 grants, including grant management
      actions like updating and revoking grants.
    x-tag-expanded: false
  - name: Jose Object
    description: API endpoints for JOSE objects.
    x-tag-expanded: false
  - name: Device Flow
    description: API endpoints for implementing OAuth 2.0 Device Flow
    x-tag-expanded: false
  - name: Federation Endpoint
    description: API endpoints for implementing OpenID Federation using Authlete.
    x-tag-expanded: false
  - name: Verifiable Credential Issuer
    description: >-
      API endpoints for implementing and running a Verifiable Credential Issuer
      (VCI).
    x-tag-expanded: false
  - name: Hardware Security Key
    description: API endpoints for managing hardware security keys (HSK).
    x-tag-expanded: false
  - name: Utility Endpoints
    description: API endpoints for various utility operations.
    x-tag-expanded: false
  - name: Native SSO
    description: API endpoints for Native SSO
    x-tag-expanded: false
paths:
  /api/{serviceId}/backchannel/authentication/fail:
    post:
      tags:
        - CIBA
      summary: Fail Backchannel Authentication Request
      description: >
        The API prepares JSON that contains an error. The JSON should be used as
        the response body of the

        response which is returned to the client from the [backchannel
        authentication
        endpoint](https://openid.net/specs/openid-client-initiated-backchannel-authentication-core-1_0.html#auth_backchannel_endpoint).
      operationId: backchannel_authentication_fail_api
      parameters:
        - in: path
          name: serviceId
          description: A service ID.
          schema:
            type: string
          required: true
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/backchannel_authentication_fail_request'
          application/x-www-form-urlencoded:
            schema:
              $ref: '#/components/schemas/backchannel_authentication_fail_request'
      responses:
        '200':
          description: ''
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/backchannel_authentication_fail_response'
              example:
                resultCode: A185001
                resultMessage: >-
                  [A185001] Successfully generated an error response for the
                  backchannel authentication request.
                action: FORBIDDEN
                responseContent: '{\"error\":\"access_denied\"}'
        '400':
          $ref: '#/components/responses/400'
        '401':
          $ref: '#/components/responses/401'
        '403':
          $ref: '#/components/responses/403'
        '500':
          $ref: '#/components/responses/500'
      x-codeSamples:
        - lang: typescript
          label: Typescript (SDK)
          source: |-
            import { Authlete } from "@authlete/typescript-sdk";

            const authlete = new Authlete({
              bearer: process.env["AUTHLETE_BEARER"] ?? "",
            });

            async function run() {
              const result = await authlete.ciba.fail({
                serviceId: "<id>",
                backchannelAuthenticationFailRequest: {
                  ticket: "<value>",
                  reason: "MISSING_USER_CODE",
                },
              });

              console.log(result);
            }

            run();
        - lang: ruby
          label: Ruby (SDK)
          source: >-
            require 'authlete_ruby_sdk'


            Models = ::Authlete::Models

            s = ::Authlete::Client.new(
              bearer: '<YOUR_BEARER_TOKEN_HERE>'
            )

            res = s.ciba.fail_request(service_id: '<id>',
            backchannel_authentication_fail_request:
            Models::Components::BackchannelAuthenticationFailRequest.new(
              ticket: '<value>',
              reason: Models::Components::BackchannelAuthenticationFailRequestReason::MISSING_USER_CODE
            ))


            unless res.backchannel_authentication_fail_response.nil?
              # handle response
            end
        - lang: go
          label: Go (SDK)
          source: "package main\n\nimport(\n\t\"context\"\n\t\"os\"\n\tauthlete \"github.com/authlete/authlete-go-sdk\"\n\t\"github.com/authlete/authlete-go-sdk/models/components\"\n\t\"log\"\n)\n\nfunc main() {\n    ctx := context.Background()\n\n    s := authlete.New(\n        authlete.WithSecurity(os.Getenv(\"AUTHLETE_BEARER\")),\n    )\n\n    res, err := s.Ciba.Fail(ctx, \"<id>\", components.BackchannelAuthenticationFailRequest{\n        Ticket: \"<value>\",\n        Reason: components.BackchannelAuthenticationFailRequestReasonMissingUserCode,\n    })\n    if err != nil {\n        log.Fatal(err)\n    }\n    if res.BackchannelAuthenticationFailResponse != nil {\n        // handle response\n    }\n}"
      x-code-samples:
        - lang: shell
          label: curl
          source: >
            curl -v -X POST
            https://us.authlete.com/api/21653835348762/backchannel/authentication/fail
            \

            -H 'Content-Type: application/json' \

            -H 'Authorization: Bearer
            V5a40R6dWvw2gMkCOBFdZcM95q4HC0Z-T0YKD9-nR6F' \

            -d '{ "ticket": "holsZhINBhum6j6MYE4yZefHuQN_kd609veKCst31p0",
            "reason": "ACCESS_DENIED" }'
        - lang: java
          label: java
          source: >
            AuthleteConfiguration conf = ...;

            AuthleteApi api = AuthleteApiFactory.create(conf);


            BackchannelAuthenticationFailRequest req = new
            BackchannelAuthenticationFailRequest();

            req.setTicket("holsZhINBhum6j6MYE4yZefHuQN_kd609veKCst31p0");

            req.setReason(BackchannelAuthenticationFailRequest.Reason.ACCESS_DENIED);


            api.backchannelAuthenticationFail(req);
        - lang: python
          source: |
            conf = ...
            api = AuthleteApiImpl(conf)

            req = BackchannelAuthenticationFailRequest()
            req.ticket = 'holsZhINBhum6j6MYE4yZefHuQN_kd609veKCst31p0'
            req.reason = BackchannelAuthenticationFailReason.ACCESS_DENIED

            api.backchannelAuthenticationFail(req)
components:
  schemas:
    backchannel_authentication_fail_request:
      type: object
      required:
        - ticket
        - reason
      properties:
        ticket:
          type: string
          description: >
            The ticket which should be deleted on a call of Authlete's
            `/backchannel/authentication/fail` API.

            This request parameter is not mandatory but optional. If this
            request parameter is given and the

            ticket belongs to the service, the specified ticket is deleted from
            the database. Giving this

            parameter is recommended to clean up the storage area for the
            service.
        reason:
          type: string
          enum:
            - ACCESS_DENIED
            - EXPIRED_LOGIN_HINT_TOKEN
            - INVALID_BINDING_MESSAGE
            - INVALID_TARGET
            - INVALID_USER_CODE
            - MISSING_USER_CODE
            - SERVER_ERROR
            - UNAUTHORIZED_CLIENT
            - UNKNOWN_USER_ID
          description: >
            The reason of the failure of the backchannel authentication request.
            This request parameter is

            not mandatory but optional. However, giving this parameter is
            recommended. If omitted, `SERVER_ERROR`

            is used as a reason.
        errorDescription:
          type: string
          description: >
            The description of the error. This corresponds to the
            `error_description` property in the response

            to the client.
        errorUri:
          type: string
          description: >
            The URI of a document which describes the error in detail. If this
            optional request parameter

            is given, its value is used as the value of the `error_uri`
            property.
    backchannel_authentication_fail_response:
      type: object
      properties:
        resultCode:
          type: string
          description: The code which represents the result of the API call.
        resultMessage:
          type: string
          description: A short message which explains the result of the API call.
        action:
          type: string
          enum:
            - INTERNAL_SERVER_ERROR
            - BAD_REQUEST
            - FORBIDDEN
          description: >-
            The next action that the authorization server implementation should
            take.
        responseContent:
          type: string
          description: >
            The content that the authorization server implementation is to
            return to the client

            application. Its format varies depending on the value of `action`
            parameter.
    result:
      type: object
      properties:
        resultCode:
          type: string
          description: The code which represents the result of the API call.
        resultMessage:
          type: string
          description: A short message which explains the result of the API call.
  responses:
    '400':
      description: ''
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/result'
          example:
            resultCode: A001201
            resultMessage: '[A001201] /auth/authorization, TLS must be used.'
    '401':
      description: ''
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/result'
          example:
            resultCode: A001202
            resultMessage: '[A001202] /auth/authorization, Authorization header is missing.'
    '403':
      description: ''
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/result'
          example:
            resultCode: A001215
            resultMessage: >-
              [A001215] /auth/authorization, The client (ID = 26837717140341) is
              locked.
    '500':
      description: ''
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/result'
          example:
            resultCode: A001101
            resultMessage: '[A001101] /auth/authorization, Authlete Server error.'
  securitySchemes:
    bearer:
      type: http
      scheme: bearer
      bearerFormat: JWT
      description: >
        Authenticate every request with a **Service Access Token** or
        **Organization Token**.

        Set the token value in the `Authorization: Bearer <token>` header.


        **Service Access Token**: Scoped to a single service. Use when
        automating service-level configuration or runtime flows.


        **Organization Token**: Scoped to the organization; inherits permissions
        across services. Use for org-wide automation or when managing multiple
        services programmatically.


        Both token types are issued by the Authlete console or provisioning
        APIs.

````