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files.upload method

The files.upload API method has been deprecated. It will stop functioning and be officially sunset on November 12, 2025.

Existing apps and integrations should migrate away from files.upload and instead leverage a combination of two API methods: files.getUploadURLExternal and files.completeUploadExternal. See Uploading files for more details on the process, and read more about the change in this changelog article.

Facts​

DescriptionUploads or creates a file.
Method Access
POST https://slack.com/api/files.upload
Scopes
Bot token:
User token:
Content types
application/x-www-form-urlencoded
application/json
Rate LimitsTier 2: 20+ per minute

Arguments​

Required arguments

tokenstringRequired

Authentication token bearing required scopes. Tokens should be passed as an HTTP Authorization header or alternatively, as a POST parameter.

Example: xxxx-xxxxxxxxx-xxxx

Optional arguments

channelsstringOptional

Comma-separated list of channel names or IDs where the file will be shared.

contentstringOptional

File contents via a POST variable. If omitting this parameter, you must provide a file.

Example: ...
fileOptional

File contents via multipart/form-data. If omitting this parameter, you must submit content.

Example: ...
filenamestringOptional

Filename of file.

Example: foo.txt
filetypestringOptional

A file type identifier.

Example: php
initial_commentstringOptional

The message text introducing the file in specified channels.

Example: Best!
thread_tsstringOptional

Provide another message's ts value to upload this file as a reply. Never use a reply's ts value; use its parent instead.

titlestringOptional

Title of file.

Example: My File

Usage info​

This method allows you to create or upload an existing file.

You must provide either a file or content parameter.

The content of the file can either be posted using an enctype of multipart/form-data (with the file parameter named file), in the usual way that files are uploaded via the browser, or the content of the file can be sent as a POST var called content. The latter should be used for creating a "file" from a long message/paste and forces "editable" mode.

In both cases, the type of data in the file will be intuited from the filename and the magic bytes in the file, for supported formats.

Sending a valid filetype parameter will override this behavior. Possible filetype values can be found in the file object definition.

Files uploaded via multipart/form-data will be stored either in hosted or editable mode, based on certain heuristics (determined type, file size).

The file can also be shared directly into channels on upload, by specifying an optional argument channels. If there's more than one channel name or ID in the channels string, they should be comma-separated. The owner of the token used to upload the file must also be a member of any channel you wish to post to this way.

There is a 1 megabyte file size limit for files uploaded as snippets.

Upload files and images into message threads by providing the thread parent's ts value with the thread_ts parameter.

The initial_comment field is used in messages to introduce the file in conversation.

If you only specify a filename, we remove the file extension and populate the file's title with the remaining value. So, if you want the file's extension to be shown in Slack, you must include it in the title argument when uploading it.

Response​

Success response after uploading a file to a channel with an initial message

{
  "ok": true,
  "file": {
    "id": "F0TD00400",
    "created": 1532293501,
    "timestamp": 1532293501,
    "name": "dramacat.gif",
    "title": "dramacat",
    "mimetype": "image/jpeg",
    "filetype": "gif",
    "pretty_type": "JPEG",
    "user": "U0L4B9NSU",
    "editable": false,
    "size": 43518,
    "mode": "hosted",
    "is_external": false,
    "external_type": "",
    "is_public": false,
    "public_url_shared": false,
    "display_as_bot": false,
    "username": "",
    "url_private": "https://.../dramacat.gif",
    "url_private_download": "https://.../dramacat.gif",
    "thumb_64": "https://.../dramacat_64.gif",
    "thumb_80": "https://.../dramacat_80.gif",
    "thumb_360": "https://.../dramacat_360.gif",
    "thumb_360_w": 360,
    "thumb_360_h": 250,
    "thumb_480": "https://.../dramacat_480.gif",
    "thumb_480_w": 480,
    "thumb_480_h": 334,
    "thumb_160": "https://.../dramacat_160.gif",
    "image_exif_rotation": 1,
    "original_w": 526,
    "original_h": 366,
    "permalink": "https://.../dramacat.gif",
    "permalink_public": "https://.../More-Path-Components",
    "comments_count": 0,
    "is_starred": false,
    "shares": {
      "private": {
        "D0L4B9P0Q": [
          {
            "reply_users": [],
            "reply_users_count": 0,
            "reply_count": 0,
            "ts": "1532293503.000001"
          }
        ]
      }
    },
    "channels": [],
    "groups": [],
    "ims": [
      "D0L4B9P0Q"
    ],
    "has_rich_preview": false
  }
}

Uploading a file with the content parameter creates an editable text/plain file by default

{
  "ok": true,
  "file": {
    "id": "F0TD0GUTS",
    "created": 1532294750,
    "timestamp": 1532294750,
    "name": "-.txt",
    "title": "Untitled",
    "mimetype": "text/plain",
    "filetype": "text",
    "pretty_type": "Plain Text",
    "user": "U0L4B9NSU",
    "editable": true,
    "size": 11,
    "mode": "snippet",
    "is_external": false,
    "external_type": "",
    "is_public": true,
    "public_url_shared": false,
    "display_as_bot": false,
    "username": "",
    "url_private": "https://.../.txt",
    "url_private_download": "https://...download/-.txt",
    "permalink": "https://.../.txt",
    "permalink_public": "https://.../.txt",
    "edit_link": "https://.../.txt/edit",
    "preview": "launch plan",
    "preview_highlight": "<div class=\"CodeMirror cm-s-default CodeMirrorServer\" oncopy=\"if(event.clipboardData){event.clipboardData.setData('text/plain',window.getSelection().toString().replace(/\\u200b/g,''));event.preventDefault();event.stopPropagation();}\">\n<div class=\"CodeMirror-code\">\n<div><pre>launch plan</pre></div>\n</div>\n</div>\n",
    "lines": 1,
    "lines_more": 0,
    "preview_is_truncated": false,
    "comments_count": 0,
    "is_starred": false,
    "shares": {
      "public": {
        "C061EG9SL": [
          {
            "reply_users": [],
            "reply_users_count": 0,
            "reply_count": 0,
            "ts": "1532294750.000001",
            "channel_name": "general",
            "team_id": "T061EG9R6"
          }
        ]
      }
    },
    "channels": [
      "C061EG9SL"
    ],
    "groups": [],
    "ims": [],
    "has_rich_preview": false
  }
}

Typical error response

{
  "ok": false,
  "error": "invalid_auth"
}

By default all newly-uploaded files are private and only visible to the owner. They become public once they are shared into a public channel (which can happen at upload time via the channels argument).

If successful, the response will include a file object.

Examples​

Upload "dramacat.gif" from the current directory and share it in two channels, using multipart/form-data:

curl -F file=@dramacat.gif -F "initial_comment=Shakes the cat" -F channels=C024BE91L,D032AC32T -H "Authorization: Bearer xoxb-xxxxxxxxx-xxxx" https://slack.com/api/files.upload

Create an editable text file containing the text "launch plan":

curl -F "content=launch plan" -H "Authorization: Bearer xoxb-xxxxxxxxx-xxxx" https://slack.com/api/files.upload

Upload another image to an existing message thread:

curl -F file=@drworm.gif -F "initial_comment=I play the drums." -F channels=C024BE91L -F thread_ts=1532293503.000001 -H "Authorization: Bearer xoxp-xxxxxxxxx-xxxx" https://slack.com/api/files.upload

Errors​

This table lists the expected errors that this method could return. However, other errors can be returned in the case where the service is down or other unexpected factors affect processing. Callers should always check the value of the ok parameter in the response.

Error
Description
access_denied

Access to a resource specified in the request is denied.

accesslimited

Access to this method is limited on the current network

account_inactive

Authentication token is for a deleted user or workspace when using a bot token.

blocked_file_type

Admin has disabled uploading this type of file

channel_not_found

At least one of the values passed for channels was invalid.

deprecated_endpoint

The endpoint has been deprecated.

ekm_access_denied

Administrators have suspended the ability to post a message.

enterprise_is_restricted

The method cannot be called from an Enterprise.

fatal_error

The server could not complete your operation(s) without encountering a catastrophic error. It's possible some aspect of the operation succeeded before the error was raised.

internal_error

The server could not complete your operation(s) without encountering an error, likely due to a transient issue on our end. It's possible some aspect of the operation succeeded before the error was raised.

invalid_arg_name

The method was passed an argument whose name falls outside the bounds of accepted or expected values. This includes very long names and names with non-alphanumeric characters other than _. If you get this error, it is typically an indication that you have made a very malformed API call.

invalid_arguments

The method was called with invalid arguments.

invalid_array_arg

The method was passed an array as an argument. Please only input valid strings.

invalid_auth

Some aspect of authentication cannot be validated. Either the provided token is invalid or the request originates from an IP address disallowed from making the request.

invalid_channel

One or more channels supplied are invalid

invalid_charset

The method was called via a POST request, but the charset specified in the Content-Type header was invalid. Valid charset names are: utf-8 iso-8859-1.

invalid_form_data

The method was called via a POST request with Content-Type application/x-www-form-urlencoded or multipart/form-data, but the form data was either missing or syntactically invalid.

invalid_post_type

The method was called via a POST request, but the specified Content-Type was invalid. Valid types are: application/json application/x-www-form-urlencoded multipart/form-data text/plain.

invalid_thread_ts

Value passed to thread_ts was invalid

malware_detected

This file may contain a virus or other malware and can't be uploaded to Slack

method_deprecated

This API is deprecated. Please refer to https://docs.slack.dev/changelog/2024-04-a-better-way-to-upload-files-is-here-to-stay

method_deprecated

The method has been deprecated.

missing_post_type

The method was called via a POST request and included a data payload, but the request did not include a Content-Type header.

missing_scope

The token used is not granted the specific scope permissions required to complete this request.

no_permission

The workspace token used in this request does not have the permissions necessary to complete the request. Make sure your app is a member of the conversation it's attempting to post a message to.

not_allowed_token_type

The token type used in this request is not allowed.

not_authed

No authentication token provided.

not_in_channel

Authenticated user is not in the channel.

org_login_required

The workspace is undergoing an enterprise migration and will not be available until migration is complete.

post_contents_too_large

File content is larger than 130kb.

posting_to_general_channel_denied

An admin has restricted posting to the #general channel.

ratelimited

The request has been ratelimited. Refer to the Retry-After header for when to retry the request.

request_timeout

The method was called via a POST request, but the POST data was either missing or truncated.

service_unavailable

The service is temporarily unavailable

slack_connect_blocked_file_type

File uploads with certain types are blocked in all Slack Connect communications

slack_connect_clip_sharing_blocked

Admin has disabled Clip sharing in Slack Connect channels

slack_connect_file_upload_sharing_blocked

Admin has disabled File uploads in all Slack Connect communications

team_access_not_granted

The token used is not granted the specific workspace access required to complete this request.

team_added_to_org

The workspace associated with your request is currently undergoing migration to an Enterprise Organization. Web API and other platform operations will be intermittently unavailable until the transition is complete.

token_expired

Authentication token has expired

token_revoked

Authentication token is for a deleted user or workspace or the app has been removed when using a user token.

two_factor_setup_required

Two factor setup is required.