Files

Sending Files

Users, both public and corporate, can exchange files in chats. Files can even be sent to yourself.

To send a file, select a chat and click the paperclip icon in the message input field. In web and desktop apps on PC, files can be dragged and dropped directly into the chat area for sending. In the mobile app, permission to access files is required to attach a file.

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Viewing Sent Files

To view a sent image or video in a chat, click, or tap on it. If the app does not support viewing due to restrictions (e.g., unsupported codecs or formats), the file will need to be downloaded to the device and viewed in a third-party app.

The built-in viewer supports not only images and videos but also documents. To view a document, click the View button in the message with the attachment. Preview is available for the following document types:

• Web/Desktop: docx, xlsx, pptx, pdf, txt. Web and desktop apps use exclusively the built-in viewer for document preview.
• Android: pdf, doc, docx, xls, xlsx, ppt, pptx, txt, html, htm. In the Android app, documents can be viewed not only in the built-in eXpress viewer but also in the system's default app that supports the format. To do this, disable the Use internal document viewer setting in the mobile app settings.
• iOS: pdf, pdf/a, doc, docx, xlsx, xls, pptx, ppt, jpg, heif, bmp, tif, png, svg, emf, gif, pages, keynote, numbers, rtf, txt, html, xps. In the iOS app, the standard system document viewer is used. In the iOS app build for ETS, the built-in internal document viewer may be used.

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File Size Limits, Image Compression

Each individual file must comply with the following size limits:

• for corporate users — no more than 1 GB;
• for public server users — no more than 25 MB.

In web and desktop apps, video files up to 50 MB in size are displayed in the message as a video that can be viewed directly in the chat. Video files larger than 50 MB are displayed as files that require downloading before viewing in a third-party app.

By default, images are compressed when sent, which may slightly reduce their quality. To send an image without compression, attach it as a "document".

MIME Type Restrictions in Web/Desktop Apps

In the web/desktop application, you can send any files except those with a prohibited MIME type. Prohibited files may include some executable files, installation files, and scripts.


If the application cannot determine the MIME type of a file, sending it will be impossible. In such cases, contact eXpress support.

MIME Types Prohibited in Web/Desktop Apps

• application/vnd.microsoft.portable-executable
• application/x-msdos-program
• application/x-ms-dos-executable
• application/x-executable
• application/x-msi
• application/x-debian-package
• application/vnd.debian.binary-package
• application/x-redhat-package-manager
• application/x-apple-diskimage
• application/mac-binhex40
• application/javascript
• application/x-javascript
• application/x-oz-application
• application/x-sh
• application/x-shellscript
• application/x-shockwave-flash
• application/x-java-archive
• application/java-archive
• application/x-xpinstall
• text/iuls

The organization's administrator may additionally prohibit other MIME types. For consultation, contact your organization's support team or eXpress support.

Role Model Restrictions for Files

If the role model is enabled and configured on the corporate server, you may encounter warnings such as "This chat has sending restrictions" or other prohibition messages. This means that the chat or channel has restrictions on sending, downloading, or forwarding attachments:

• by file size, for example: "Forwarding videos over 300 MB is restricted," "This chat has restrictions on sending documents over 20 MB";
• by file extension, for example: "Disallowed sending of: docx", "This chat has restrictions on sending images in this format";
• by user type or specific users in the chat, for example: "Images are not allowed to be forwarded into chat with the user ...";
• by action type — sharing, viewing, downloading, or forwarding a file may be prohibited, for example: "You are not allowed to forward videos from this chat", "This chat has restrictions on viewing attachments".

Attachments subject to restrictions may be marked with an error icon or accompanied by a corresponding warning. Such attachments can only be deleted (except for attachments created within the app, such as photos — they can be downloaded to the device).

For more information about the restrictions, click or tap on the Learn more label or the information button in the pop-up warning.

For a detailed description of all role model restrictions for working with files and their application in chats and Smart Apps, see the section "Role Model Rules".

Contour Restrictions on Sending Files

In the corporate server settings, administrator can restrict file sharing and screen sharing access, allowing it only for users within the contour — the internal corporate data transmission system (CDTS). If contour access is enabled, users from external networks may receive the error "Available only from the company network" when trying to view a file. Users within the contour will not be able to open files from users outside the contour due to the error "You have no access to this file." To check or configure these restrictions, contact your organization's support team or eXpress support.

Files exchanged by users in a chat are uploaded to the servers of all chat participants.

Files used in Smart Apps (for example, images in the news feed or documents from the HR Smart App) are also stored on the corporate server.

By default, files are stored on the server indefinitely. The corporate server administrator can set a storage limit in days separately for documents, media files, voice recordings, and call recordings. If a file is deleted due to the expiration of the storage period, the user will receive the message This file is unavailable when attempting to download it.

For Administrators: How to Configure File Storage Duration on the Server

In the corporate server admin panel, under the File Service section, enable the cleanup of old files and specify the number of days before their automatic deletion.

The corporate server administrator can enable antivirus scanning of sent files and integration with a DLP system. A file that fails the scan will not be sent. Configuring antivirus scanning and DLP is done in the separate console that manages the integration of the server with the antivirus and DLP system. Detailed information is available in the administrator guide in the Product Documentation section.

Unable to Attach an Image or Video to a Message in the Mobile App

Check the mobile app's access settings to the gallery. On iOS devices, you need to grant access to all photos: Settings > select the app > Photos > choose All Photos.

Unable to Download a File Due to the Error "File is Unavailable"

This error can occur for several reasons:

• The file's storage period on the server has expired. The corporate server administrator may have configured automatic file cleanup after a certain number of days. To check if the file was deleted for this reason, contact your organization's support team.
  For Administrators: How to Check the File Storage Duration on the Server

  To check the storage duration, follow these steps:

  • Determine the file's sending date.
  • In the corporate server admin panel, under the File Service section, check if the cleanup of old files (retention) is enabled and how many days are set before automatic deletion.
  • If the file was sent before the set period, it was automatically deleted and can no longer be downloaded.
• The file is not yet ready for download. In mixed chats with participants from different servers, the file is first uploaded from another server to your server and only then becomes available for download. Try restarting the mobile app or refreshing the cache in the web/desktop app by pressing Ctrl (Cmd) + R. If the issue persists, contact your organization's support team to check the file service on the server.
  For Administrators: Collecting Diagnostics

  For diagnostics, collect logs from the mobile app or network requests information from the console (under the Network tab) in the web/desktop app, as well as container logs for the File Service on the sender's server, and send them to eXpress support.
• A file sent by an external user may be unavailable in your organization's local network. Files from public users are delivered to corporate users via third-party storage — the Yandex Cloud. If access to this cloud is restricted in your organization, a corporate user will not be able to receive a file from an external user. Registering the external user on the same corporate server will resolve this issue. For more information, contact eXpress support.

Unable to Send or Download Files in All Chats

There is an issue with the corporate server. Contact your organization's support team or eXpress support to resolve the issue.

For Administrators: Diagnosing File Service Issues on the Server

Most often, such issues are related to a failure in the File Service on the server.

• Collect container logs for the File Service on the server and send them to eXpress support for analysis.
• If necessary, restart the File Service container via the console and ask the user to try again.
• Check the ability to send and download files.

Unable to View an Attached File

The app supports viewing certain file types within eXpress. Preview and thumbnail generation in the chat are not possible if the file is corrupted, its format is unsupported by the app, or if it is a media file lacking the necessary codec or containing incorrectly encoded content (e.g., incorrect placement of keyframes or video metadata).

Try refreshing the local cache of the app if an error occurs when attempting to view the file.

If this does not help, in the web/desktop app, download the file to your computer and open it in a third-party application. In the mobile app, disable the Use internal viewer setting and try opening the file again.

After Viewing a File, the Desktop App Remains in Full-Screen Mode

To exit the app's full-screen mode, press the (Fn +) F11 key.

Unable to Forward a File from Another App to eXpress

If you are unable to forward a file, image, or document from another app to eXpress or vice versa on a mobile device, contact eXpress support for diagnostics.

"You Cannot Send Files to This Chat" When Trying to Send a File to a Chat with Disabled End-to-End Encryption

If the error "You cannot send files to this chat" occurs when trying to send a file to a group chat or channel with disabled end-to-end encryption, this means such actions are prohibited by the Trust and Local settings for the corporate data transfer system contour on the corporate server. To clarify the contour settings, contact your organization's support team.