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Removed and Deprecated Features

This page describes features that are removed from support for Mattermost, or will be removed in a future update (deprecated), and provides early notice about future changes that might affect your use of Mattermost. This information is subject to change with future releases, and might not include each deprecated feature.

Upcoming deprecations​

Mattermost Desktop App v6.4 (November 2026)​

  • Starting with Mattermost Desktop App v6.4 (November 2026), servers configured with a subpath in their Site URL will require Boards v9.4.0 or later. The Desktop App will no longer strip the server subpath from paths sent by Boards, a workaround that caused "Team not found" errors when a team name matched the subpath, so older Boards versions may show navigation errors. Update the Boards plugin to v9.4.0 or later before updating the Desktop App. Follow the Boards installation instructions. Deployments without a subpath will be unaffected. See the forum post for full details and migration options.

Removed features by Mattermost version​

Mattermost Server v12.0 (October 2026)​

  • RHEL 7 and RHEL 8 are no longer supported deployment targets. Debian Bullseye reached end-of-life in August 2026, and the v12.0 server binaries now require glibc 2.34 or later — incompatible with RHEL 7 (glibc 2.17) and RHEL 8 (glibc 2.28). Mattermost v11.11 (September 2026) was the last release to support RHEL 7 and RHEL 8. RHEL 9, Ubuntu 22.04/24.04 LTS, Debian Bookworm, and container-based deployments remain fully supported. Admins running RHEL 7 or RHEL 8 should upgrade to RHEL 9 or migrate to another supported platform. See the forum post for full details and migration options.
  • OpenSearch 1.x is no longer a supported search backend. OpenSearch 1.x reached end-of-life on May 6, 2025, and the minimum supported version is now OpenSearch 2.x. Mattermost v12.0 is the first release to require OpenSearch 2.x or newer; v11 releases continue to work with 1.x while admins plan their migration. OpenSearch 2.x, 3.x, and Elasticsearch 8.x/9.x remain fully supported search backends. Admins running OpenSearch 1.x should upgrade to 2.x, or migrate to Elasticsearch. See the forum post for full details and migration options.
  • atmos/camo is no longer supported as an image proxy. The atmos/camo project has been archived and is no longer maintained. If ImageProxySettings.ImageProxyType is set to atmos/camo, the server automatically switches it to the built-in local image proxy (local) on startup and logs a warning; the RemoteImageProxyURL and RemoteImageProxyOptions settings have also been removed and are ignored. If image proxying is enabled, the Mattermost server then fetches images itself, so it must be able to reach the external hosts that images are loaded from. Admins who don't want image proxying can set ImageProxySettings.Enable to false. The local proxy requires no external service and includes SVG content blocking and security response headers. See the forum post for full details and migration options.
  • The Mattermost web and desktop apps are built on React 19. This only affects plugins that register web app (frontend) components — server-only plugins are unaffected. Web app plugins use the React version provided by the web app, so your plugin's components render under React 19 whether or not you rebuild. Plugins that call APIs removed in React 19 (ReactDOM.findDOMNode, propTypes/defaultProps on function components, legacy Context, string refs) or depend on legacy synchronous rendering may break. To fix a broken plugin, run npx codemod@latest react/19/migration-recipe and correct any removed-API usage. See the forum post for full details.
  • User sessions and personal access tokens (PATs) can no longer set post identity or display-override props. Some deployments relied on forging props such as from_webhook with override_username and override_icon_url so posts appeared under a custom name and icon — a pattern indistinguishable from impersonation. The server now strips these props from client and PAT payloads and re-applies them only under verified integration authority. Posts are still created, but forged props are silently removed and the message appears as the authenticating user, with no error returned. Legitimate integrations are unaffected: incoming webhooks and slash commands can still override the username and icon when enabled in the System Console, and bots post as the bot account. Admins relying on PAT forging should migrate those scripts to an incoming webhook or bot account. See the forum post for full details and migration options.
  • Deprecated interactive dialog date/datetime fields have been removed. Top-level min_date, max_date, and time_interval, and datetime_config.allow_manual_time_entry, are no longer accepted; use datetime_config (with manual_time_entry) instead. Legacy keys are silently ignored.
  • Deprecated Slack compatibility type aliases and functions have been removed from the go package (SlackAttachment, SlackAttachmentField, ParseSlackAttachment, StringifySlackFieldValue). Use MessageAttachment, MessageAttachmentField, ParseMessageAttachment, and StringifyMessageAttachmentFieldValue instead.
  • A set of unused configuration settings has been removed: ElasticsearchSettings.BulkIndexingTimeWindowSeconds, ClusterSettings.EnableExperimentalGossipEncryption, ExperimentalSettings.ClientSideCertEnable, TeamSettings.ExperimentalViewArchivedChannels, CloudSettings.CWSMock, PluginSettings.ChimeraOAuthProxyURL, DataRetentionSettings.EnableBoardsDeletion, DataRetentionSettings.BoardsRetentionDays, SqlSettings.AtRestEncryptKey, NativeAppSettings.EnableIntuneMAM, and GuestAccountsSettings.AllowEmailAccounts. Removed fields present in an existing config.json are ignored and the server starts normally, so no configuration changes are required. Admins using NativeAppSettings.EnableIntuneMAM should use IntuneSettings.Enable instead.
  • The LocalizationSettings.EnableExperimentalLocales configuration setting has been removed, along with most of the work-in-progress translation catalogs it exposed. Danish is now a supported language, and Czech, Croatian, Finnish, Lithuanian, Norwegian Bokmål and Portuguese (Portugal) are available to all users as experimental languages without the setting. Users who had selected any other removed language see Mattermost in English. The setting is ignored if left in an existing config.json.
  • Removed the Belarusian language. Users who had Belarusian selected now see the default language.
  • Support for PostgreSQL v14 and earlier has been removed. The new minimum PostgreSQL version is v15+. See the minimum supported PostgreSQL version policy documentation for details.
  • The built-in Slack import API and CLI have been removed. The POST /teams/{team_id}/import endpoint and the mattermost import slack command are no longer available. Use the mmetl tool with mmctl import instead.
  • The MoveThreadsEnabled feature flag is no longer supported. If it is enabled, the server turns it off on startup and logs a warning. Use the Wrangler plugin to move threads between channels instead.
  • The AppsEnabled feature flag is no longer supported. If it is set to true, the server turns it off on startup and logs a warning.
  • The required format query parameter has been removed from the GET /api/v4/license/client endpoint. The endpoint now returns the client license information without requiring format specification.
  • The System Console > System Attributes > User Attributes page has been removed on Enterprise plans. Existing Custom Profile Attributes (User Attributes) fields are migrated automatically into Attribute Management on server startup and are managed there from v12.0. The old page's URL redirects to Attribute Management.
  • PATCH and DELETE requests to /api/v4/custom_profile_attributes/fields/{field_id} now return HTTP 400 when the field is linked to an Attribute Management template, with an error pointing to the Global Attributes API. On Enterprise plans, eligible existing User Attributes fields are linked to templates automatically on server startup, so scripts and integrations that edit or delete these fields through the User Attributes API must use the Global Attributes API instead.
  • The EnableConcurrentReact feature flag has been removed. The web app now always renders with concurrent React, and the flag is ignored if it is still set.
  • The EmailLoginButtonColor, EmailLoginButtonBorderColor, and EmailLoginButtonTextColor client configuration fields have been removed, along with the EmailSettings login button color settings. These fields were never applied by any client.
  • The channel member API endpoints no longer return last_viewed_at and last_update_at for other users' memberships. They previously returned an invalid value of -1; the fields are now omitted from the response when they belong to a user other than the requester. Clients reading those fields for other users must handle their absence.
  • ServiceSettings.ExperimentalEnableHardenedMode is deprecated and replaced by ServiceSettings.EnableHardenedMode, which has moved from System Console > Experimental > Features to System Console > Environment > Web Server. An existing value is carried over to EnableHardenedMode automatically on upgrade. After that, the server reads only EnableHardenedMode, so update any configuration management, environment variables, or scripts that still set the old setting.

Mattermost Mobile App v2.45 (October 2026)​

  • Removed support for iOS v17 and earlier and Android v10 and earlier, raising the minimum supported mobile operating systems to iOS v18 and Android v11. Devices running earlier operating system versions no longer receive new versions of the app from the App Store or Google Play; the installed version continues to work but receives no further updates, including security fixes. See more details in this forum post.

Mattermost Desktop App v6.1 (March 2026)​

  • The in-app auto-updater for Windows and Linux AppImage installations has been deprecated. See more details in this forum post.

Mattermost Server v11.4 (February 2026)​

  • Photoshop Document (PSD) files are now no longer inline previewed, they are treated as regular file attachments. This change has also been applied to v11.3.1, v11.2.3, and v10.11.11 (Extended Support Release) dot releases.

Mattermost Mobile App v2.36.4 (January 2026)​

  • Removed support for iOS v15 and updated the iOS minimum version to v16. See more details in this forum post.

Mattermost Server v11.1 (November 2025)​

  • The version of React used by the Mattermost web app has been updated from React 17 to React 18. See more details in this forum post.

Mattermost Server v11.0 (October 2025)​

  • GitLab SSO has been deprecated from Team Edition. Deployments using GitLab SSO can remain on v10.11 ESR (with 12 months of security updates) while transitioning to our new free offering Mattermost Entry, or can explore commercial/nonprofit options. See more details in this forum post.

  • The TeamSettings.ExperimentalViewArchivedChannels setting has been deprecated. Archived channels will always be accessible, subject to normal channel membership. The server will fail to start if this setting is set to false. To deny access to archived channels, mark them as private and remove affected channel members. See more details in this forum post.

  • Playbooks has stopped working for Team Edition. Entry, Professional, Enterprise, and Enterprise Advanced plans are automatically upgraded to Playbooks v2 with no expected downtime. See more details in this forum post.

  • Experimental Bleve Search functionality has been retired. If Bleve is enabled, search will not work until DisableDatabaseSearch is set to false. See more details in this forum post.

  • Support for MySQL has ended. Our Migration Guide outlines the steps, tools and support available for migrating to PostgreSQL. See more details in this forum post.

  • The registerPostDropdownMenuComponent hook in the web app’s plugin API has been removed in favour of registerPostDropdownMenuAction. See more details in this forum post.

  • The web app is no longer exposing the Styled Components dependency for use by web app plugins. See more details in this forum post.

  • Omnibus support has been deprecated. The last mattermost-omnibus release was v10.12. See more details in this forum post.

  • Deprecated include_removed_members option in api/v4/ldap/sync has been removed. Admins can use the LDAP setting ReAddRemovedMembers.

  • Customers that have the NPS plugin enabled can remove it as it no longer sends the feedback over through telemetry.

  • Format query parameter requirement in the /api/v4/config/client endpoint has been deprecated.

  • Removed deprecated mmctl commands and flags:

    • channel add - use channel users add
    • channel remove - use channel users remove
    • channel restore - use channel unarchive
    • channel make-private - use channel modify --private
    • command delete - use command archive
    • permissions show - use permissions role show
    • mmctl user email - use mmctl user edit email
    • mmctl user username - use mmctl user edit username

  • Experimental certificate-based authentication feature has been removed. ExperimentalSettings.ClientSideCertEnable must be false to start the server.

  • Added logic to migrate the password hashing method from bcrypt to PBKDF2. The migration will happen progressively, migrating the password of a user as soon as they enter it; e.g. when logging in or when double-checking their password for any sensitive action. There is an edge case where users might get locked out of their account: if a server upgrades to v11 and user A logs in (i.e., they need to enter their password), and then the server downgrades to v10.12 or previous, user A will no longer be able to log in. In this case, admins will need to manually reset the password of such users, through the system console or through the mmctl user reset-password [users] command. The new password hashing method is more CPU-intensive. Admins of servers with password-based login should monitor the performance on periods where many users log in at the same time.

  • /api/v4/teams/{team_id}/channels/search_archived has been deprecated in favour of /api/v4/channels/search with the deleted parameter.

  • Separate notification log file has been deprecated. If admins want to continue using a separate log file for notification logs, they can use the AdvancedLoggingJSON configuration. An example configuration to use is:

{
  "LogSettings": {
    "AdvancedLoggingJSON": {
      "notifications_file": {
        "type": "file",
        "format": "json",
        "levels": [
            {"id": 300, "name": "NotificationError"},
            {"id": 301, "name": "NotificationWarn"},
            {"id": 302, "name": "NotificationInfo"},
            {"id": 303, "name": "NotificationDebug"},
            {"id": 304, "name": "NotificationTrace"}
        ],
        "options": {
            "filename": "notifications.log",
            "max_size": 100,
            "max_age": 0,
            "max_backups": 0,
            "compress": true
        }, 
        "maxqueuesize": 1000 
      }
    }
  }
}

Mattermost Server v10.8.0​

Mattermost Server v10.6.0​

Mattermost Server v10.5.0​

  • The Mattermost server has stopped supporting manual plugin deployment. Plugins were deployed manually when an administrator or some deployment automation copies the contents of a plugin bundle into the server's working directory. If a manual or automated deployment workflow is still required, administrators can instead prepackage the plugin bundles. See more details in this forum post.
  • Mattermost has stopped official Mattermost server builds for the Microsoft Windows operating system. Administrators should migrate existing Mattermost server installations to use the official Linux builds. See more details in this forum post.

Mattermost Mobile App v2.25.0​

  • In the Mattermost Mobile App v2.25, Mattermost has stopped supporting iOS versions 13 and 14. Users should update their iOS version to v15.1 or newer. See more details in this forum post.

Mattermost Server v10.4.0​

  • The ability to import Slack themes as Mattermost themes is no longer supported.

Mattermost Server v10.3.0​

Mattermost Server v10.2.0​

  • Docker Content Trust (DCT) for signing Docker image artifacts has been replaced by Sigstore Cosign in v10.2 (November, 2024). If you rely on artifact verification using DCT, please transition to using Cosign. See this forum post for more details.

Mattermost Server v10.0.0​

  • We no longer support new installations using MySQL starting in v10. All new customers and/or deployments will only be supported with the minimum supported version of the PostgreSQL database. End of support for MySQL is targeted for Mattermost v11.
  • Apps Framework is deprecated for new installs. Please extend Mattermost using webhooks, slash commands, OAuth2 apps, and plugins.
  • Fully deprecated the /api/v4/image endpoint when the image proxy is disabled.
  • Removed deprecated Config.ProductSettings, LdapSettings.Trace, and AdvancedLoggingConfig configuration fields.
  • Removed deprecated pageSize query parameter from most API endpoints.
  • Deprecated the experimental Strict CSRF token enforcement. This feature will be fully removed in Mattermost v11.

Mattermost Server v9.9.0​

  • Removed support for self-serve purchases of Mattermost Subscriptions in various flows, throughout Cloud and Self Hosted environments.
  • Removed support for self-serve true up review submission in the System Console.

Mattermost Server v9.5.0​

  • MySQL v5.7 is at end of life. We recommend all customers to upgrade to at least 8.x. From Mattermost v9.5, which is the latest Extended Support Release, we have stopped supporting MySQL v5.7 altogether.

Mattermost Server v9.0.0​

  • Mattermost Boards and various other plugins have transitioned to being fully community supported. See this forum post for more details.
  • Removed the deprecated Insights feature.

Mattermost Server v8.0.0​

  • Removed ExperimentalSettings.PatchPluginsReactDOM. If this setting was previously enabled, confirm that:
    • All Mattermost-supported plugins are updated to the latest versions.
    • Any other plugins have been updated to support React 17. See the Important Upgrade Notes for v7.7 for more information.
  • Deprecated Insights for all new instances and for existing servers that upgrade to Mattermost v8.0.
  • Removed deprecated PermissionUseSlashCommands.
  • Removed deprecated model.CommandArgs.Session.
  • Removed support for PostgreSQL v10. The new minimum PostgreSQL version is now v11.
  • Deprecated the AdvancedLoggingConfig fields, and replaced them with AdvancedLoggingJSON fields which accept inline JSON or a filename.

Mattermost Server v6.0.0​

Mattermost Server v5.38.0​

  • In the v5.38 release (August 16, 2021), the “config watcher” (the mechanism that automatically reloads the “config.json“ file), has been removed in favor of the “mmctl config“ command that will need to be run to apply configuration changes after they are made. This change will improve configuration performance and robustness.

Mattermost Server v5.37.0​

  • The “platform“ binary and “–platform” flag have been removed. If you are using the “–platform” flag or are using the “platform“ binary directly to run the Mattermost server application via a systemd file or custom script, you will be required to use only the “mattermost“ binary.

Mattermost Server v5.32.0​

  • TLS versions 1.0 and 1.1 have been deprecated by browser vendors. Starting in Mattermost Server v5.32 (February 16), mmctl returns an error when connected to Mattermost servers deployed with these TLS versions and System Admins will need to explicitly add a flag in their commands to continue to use them. We recommend upgrading to TLS version 1.2 or higher.

Mattermost Server v5.30.0​

  • PostgreSQL ended long-term support for version 9.4 in February 2020. From v5.26 Mattermost officially supports PostgreSQL version 10 as PostgreSQL 9.4 is no longer supported. New installs will require PostgreSQL 10+. Previous Mattermost versions, including our current ESR, will continue to be compatible with PostgreSQL 9.4. PostgreSQL 9.4 and all 9.x versions are now fully deprecated in our v5.30 release (December 16). Please follow the instructions under the Upgrading Section within the PostgreSQL documentation.

Mattermost Server v5.16.0​

  • Removed support for Internet Explorer (IE11) in Mattermost v5.16.0. Learn more in our forum post.

Mattermost Server v5.12.0​

  • ExperimentalEnablePostMetadata setting was removed. Post metadata, including post dimensions, is now stored in the database to correct scroll position and eliminate scroll jumps as content loads in a channel.

Mattermost Server v5.6.0​

  • Removed support for WebRTC in beta, and replaced it with other video and audio calling solutions.
  • Removed support for IE11 Mobile View due to low usage and instability in order to invest that effort in maintaining a high quality experience on other more used browsers. End users on IE11 will thus have an increased minimum screen size. Mobile View is still supported on Chrome, Firefox, Safari, Edge as well as the desktop apps.

Mattermost Server v5.0.0​

  • All API v3 endpoints removed. API v3 endpoints are no longer supported as of Mattermost v4.6 release on January 16th, 2018, and are replaced by API v4 endpoints which were released on July 16th, 2017. See https://api.mattermost.com to learn more.
  • Desktop Notification Duration in Account Settings removed due to inconsistencies on various browsers and operating systems.
  • An unused “ExtraUpdateAt” field removed from the channel model.
  • platform binary renamed to mattermost for a clearer install and upgrade experience. All command line tools, including the bulk loading tool and developer tools, also renamed from platform to mattermost.
  • Slash commands configured to receive a GET request now have the payload encoded in the query string instead of receiving it in the body of the request, consistent with standard HTTP requests. Although unlikely, this could break custom slash commands that use GET requests incorrectly.
  • A new config.json setting to whitelist types of protocols for auto-linking added.
  • A new config.json setting to disable the permanent APIv4 delete team parameter added. The setting is off by default for all new and existing installs, except those deployed on GitLab Omnibus. A System Admin can enable the API v4 endpoint from the config.json file.

Mattermost Server v4.9.0​

  • A number of permissions configuration settings will be migrated to roles in the database, and changing their config.json values will no longer take effect. These permissions can still be modified by their respective System Console settings. See changelog for more details.

Mattermost Server v4.0.0​

  • System Console settings in Files > Images, including:
    • Image preview height and width
    • Profile picture height and width
    • Image thumbnail height and width
  • Font setting in Account Settings > Display
  • Teammate Name Display setting moved to the System Console

Mattermost Server v3.8.0​

  • Old CLI tool (replaced by an upgraded CLI tool)
  • APIv3 endpoints:
    • “GET at /channels/more” (replaced by “/channels/more/{offset}/{limit}”)
    • “POST at /channels/update_last_viewed_at” (replaced by “/channels/view”)
    • “POST at /channels/set_last_viewed_at” (replaced by “/channels/view”)
    • “POST at /users/status/set_active_channel” (replaced by “/channels/view”)

Mattermost Server v3.7.0​

  • “ServiceSettings: SegmentDeveloperKey” setting in config.json