Attach Files to a Task tasks.task.file.attach

If you are developing integrations for Bitrix24 using AI tools (Codex, Claude Code, Cursor), connect to the MCP server so that the assistant can utilize the official REST documentation.

Scope: tasks

Who can execute the method: task Creator or a user with edit access to the task

The method tasks.task.file.attach adds files from Drive to a task. The user must have read access to the file or higher.

Method Parameters

Required parameters are marked with *

Name
type

Description

taskId*
integer

The identifier of the task to which files need to be attached.

The task identifier can be obtained when creating a new task or by using the old method of getting the task list

fileIds*
array<integer>

An array of file identifiers from Drive.

File identifiers can be obtained in two ways.

Use one of the file upload methods:

Use one of the methods to get the list of files:

Code Examples

How to Use Examples in Documentation

The new API call differs by the addition of the /api/ parameter in the request:

https://{installation_address}/rest/api/{user_id}/{webhook_token}/tasks.task.file.attach

cURL (Webhook)

cURL (OAuth)

PHP

BX24.js

PHP CRest

curl -X POST \
        -H "Content-Type: application/json" \
        -H "Accept: application/json" \
        -d '{"taskId":8017,"fileIds":[1065,1077]}' \
        https://**put_your_bitrix24_address**/rest/api/**put_your_user_id_here**/**put_your_webhook_here**/tasks.task.file.attach

curl -X POST \
        -H "Content-Type: application/json" \
        -H "Accept: application/json" \
        -d '{"taskId":8017,"fileIds":[1065,1077],"auth":"**put_access_token_here**"}' \
        https://**put_your_bitrix24_address**/rest/api/tasks.task.file.attach

The SDK does not currently support calls to the address /rest/api/. Use direct HTTP requests, for example, via curl or fetch.

try
        {
            const response = await $b24.callMethod(
                'tasks.task.file.attach',
                {
                    taskId: 8017,
                    fileIds: [1065, 1077],
                }
            );
            
            const result = response.getData().result;
            console.log('Files attached:', result);
            
            processResult(result);
        }
        catch( error )
        {
            console.error('Error:', error);
        }

The SDK does not currently support calls to the address /rest/api/. Use direct HTTP requests, for example, via curl or fetch.

try {
            $response = $b24Service
                ->core
                ->call(
                    'tasks.task.file.attach',
                    [
                        'taskId' => 8017,
                        'fileIds' => [1065, 1077]
                    ]
                );
        
            $result = $response
                ->getResponseData()
                ->getResult();
        
            echo 'Success: ' . print_r($result, true);
            processData($result);
        
        } catch (Throwable $e) {
            error_log($e->getMessage());
            echo 'Error attaching file: ' . $e->getMessage();
        }

The SDK does not currently support calls to the address /rest/api/. Use direct HTTP requests, for example, via curl or fetch.

BX24.callMethod(
            'tasks.task.file.attach',
            {
                taskId: 8017,
                fileIds: [1065, 1077]
            },
            function(result){
                console.info(result.data());
                console.log(result);
            }
        );

The SDK does not currently support calls to the address /rest/api/. Use direct HTTP requests, for example, via curl or fetch.

require_once('crest.php');
        
        $result = CRest::call(
            'tasks.task.file.attach',
            [
                'taskId' => 8017,
                'fileIds' => [1065, 1077]
            ]
        );
        
        echo '<PRE>';
        print_r($result);
        echo '</PRE>';

Response Handling

HTTP Status: 200

{
            "result": {
                "result": true
            },
            "time": {
                "start": 1765357239,
                "finish": 1765357239.724951,
                "duration": 0.7249510288238525,
                "processing": 0,
                "date_start": "2025-12-10T12:00:39+01:00",
                "date_finish": "2025-12-10T12:00:39+01:00",
                "operating_reset_at": 1765357839,
                "operating": 0
            }
        }

Returned Data

Name
type

Description

result
boolean

The root element of the response.

Contains an object with the key result and the value true if the file was successfully attached

time
time

Information about the request execution time

Error Handling

HTTP Status: 400

{
            "error": {
                "code": "BITRIX_REST_V3_EXCEPTION_VALIDATION_REQUESTVALIDATIONEXCEPTION",
                "message": "Error validating the request object",
                "validation": [
                    {
                        "message": "The required field `taskId` is missing",
                        "field": "taskId"
                    }
                ]
            }
        }

Name `type`	Description
error.code `string`	String error code. Use it to identify the type of exception
error.message `string`	Text description of the error
error.validation `array`	Array with error details. Present only in data validation errors `BITRIX_REST_V3_EXCEPTION_VALIDATION_REQUESTVALIDATIONEXCEPTION`
error.validation[].field `string`	Name of the field where the validation error occurred
error.validation[].message `string`	Description of the error related to the specified field

Possible Error Codes

Request Validation Errors

Error Code: BITRIX_REST_V3_EXCEPTION_VALIDATION_REQUESTVALIDATIONEXCEPTION

Field	Error Description	How to Fix
`taskId` `fileIds`	The required field `#FIELD#` is missing	Add the specified field to the request body
`#FIELD#`	The field `#FIELD#` requires data type `#TYPE#` for this request	Ensure the provided value is of the correct type
—	Insufficient permissions	No access to the specified file or task

Statuses and System Error Codes

HTTP Status: 20x, 40x, 50x

The errors described below may occur when calling any method.

Status	Code Error Message	Description
`500`	`INTERNAL_SERVER_ERROR` Internal server error	An internal server error has occurred. Please contact the server administrator or Bitrix24 technical support
`500`	`ERROR_UNEXPECTED_ANSWER` Server returned an unexpected response	An internal server error has occurred. Please contact the server administrator or Bitrix24 technical support
`503`	`QUERY_LIMIT_EXCEEDED` Too many requests	The request intensity limit has been exceeded
`405`	`ERROR_BATCH_METHOD_NOT_ALLOWED` Method is not allowed for batch usage	The current method is not permitted for calls using batch
`400`	`ERROR_BATCH_LENGTH_EXCEEDED` Max batch length exceeded	The maximum length of parameters passed to the batch method has been exceeded
`401`	`NO_AUTH_FOUND` Wrong authorization data	Invalid access token or webhook code
`400`	`INVALID_REQUEST` Https required	The HTTPS protocol is required for method calls
`503`	`OVERLOAD_LIMIT` REST API is blocked due to overload	The REST API is blocked due to overload. This is a manual individual block; please contact Bitrix24 technical support to lift it
`403`	`ACCESS_DENIED` REST API is available only on commercial plans	The REST API is only available on commercial plans
`403`	`INVALID_CREDENTIALS` Invalid request credentials	The user associated with the access token or webhook used to call the method lacks the necessary permissions
`404`	`ERROR_MANIFEST_IS_NOT_AVAILABLE` Manifest is not available	The manifest is not available
`403`	`insufficient_scope` The request requires higher privileges than provided by the webhook token	The request requires higher privileges than those provided by the webhook token
`401`	`expired_token` The access token provided has expired	The provided access token has expired
`403`	`user_access_error` The user does not have access to the application	The user does not have access to the application. This means that the application is installed, but the portal administrator has restricted access to this application to specific users only
`500`	`PORTAL_DELETED` Portal was deleted	The public part of the site is closed. To open the public part of the site on an on-premise installation, disable the "Temporary closure of the public part of the site" option. Path to the setting: Desktop > Settings > Product Settings > Module Settings > Main Module > Temporary closure of the public part of the site

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Overview of Methods

Attach Files to a Task tasks.task.file.attach

Method ParametersMethod Parameters

Code ExamplesCode Examples

Response HandlingResponse Handling

Returned DataReturned Data

Error HandlingError Handling

Possible Error CodesPossible Error Codes

Request Validation ErrorsRequest Validation Errors

Statuses and System Error CodesStatuses and System Error Codes

Continue LearningContinue Learning

Method Parameters

Code Examples

Response Handling

Returned Data

Error Handling

Possible Error Codes

Request Validation Errors

Statuses and System Error Codes

Continue Learning