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Firefox administrator reference

Firefox Release Notes for Enterprise

Firefox 158 Latest

Upcoming, not yet released.

These changes apply to Firefox 158 and Firefox ESR 153.5.0 unless explicitly stated. Firefox ESR 153 is the current ESR.

New in Firefox 158

  • ClearOnShutdown: Clear browsing data when the browser closes. Supersedes SanitizeOnShutdown, which is ignored when both are set. (bug 2040977)

New in Firefox ESR 153.5.0

  • ClearOnShutdown: Clear browsing data when the browser closes. Supersedes SanitizeOnShutdown, which is ignored when both are set. (bug 2040977)

Changes

  • SitePolicies: Added a Container option to load matching sites in a dedicated container, with ephemeral to clear its data after the last tab closes and at shutdown. Firefox 158 only. (bug 2045801, bug 2045798)
  • ContentAnalysis: Added InterceptionPoints.ClipboardCopy to send data copied from web content to the DLP agent. Off by default, so existing deployments are unaffected. Firefox 158 only. (bug 2067877)
  • ExtensionSettings: An entry with update_url but no install_url now installs the add-on from the update manifest, so self-hosted add-ons no longer need an install_url. Firefox 158 only. (bug 2061439)
  • DisableDeveloperTools: Now also disables Marionette and the Remote Agent, so browser automation tools that rely on them no longer work while the policy is set.
  • Extensions: Add-ons listed in Uninstall are now removed at every startup, not only when the policy changes.
  • The illustration on network error pages can be hidden by setting browser.netError.illustration.enabled to false. Administrators may want to set this using the Preferences policy. Firefox 158 only. (bug 2061552)

Fixes

  • Policy URL fields rejected some valid URLs, such as internationalized domain names, non-ASCII paths and URLs containing spaces. (bug 2067819)
  • SanitizeOnShutdown: When the policy turned clearing on, Manage Exceptions and the category settings in Firefox Settings were disabled too, even for categories the policy left unset. Firefox 158 only. (bug 2065295)
  • DisableFirefoxAccounts: The toolbar could report a signed-in account when accounts were disabled. Firefox 158 only. (bug 2066062)
  • The Labs quick action in the address bar was still shown when Firefox Labs was turned off with UserMessaging, and Manage AI was still shown when browser.preferences.aiControls was false. Firefox 158 only. (bug 2070378)
  • WebsiteFilter: Blocking is now applied more consistently to redirected and embedded content.
  • Site lists in policies such as Permissions and PopupBlocking now also apply when a host is written with a trailing dot, such as example.com..
  • A policy set to null could stop other policies from applying.
  • The toolkit.policies.perUserDir preference is now only adhered to in automated testing.

Notes

  • Firefox ESR 140 is no longer supported. Firefox ESR 140.17.0, released with Firefox 157, was its final build.

Firefox 157

These changes apply to Firefox 157 and Firefox ESR 153.4.0 unless explicitly stated. Firefox ESR 153 is the current ESR.

Changes

  • AIControls: Added a SpeechRecognition option to make on-device speech recognition available or block it, with Locked to prevent users from changing it. Firefox 157 only. (bug 1940906)
  • about:policies now shows an error for a policy that only partially applied, naming the entry that failed, instead of listing it as active. (bug 2067123)

Fixes

  • Homepage: In Firefox 154 and Firefox ESR 153.1.0, setting URL to several homepages separated by | stopped working after policy validation changes. The pipe separator is accepted again, and the extra URLs are treated as Additional. (bug 2067248)
  • Handlers: An invalid mimeTypes entry caused every later entry, including the extensions and schemes blocks, to be discarded. Invalid entries are now skipped individually. (bug 2067099)

Notes

  • Firefox ESR 140 goes out of support with this release. Firefox ESR 140.17.0 is its final build.

Firefox 156

These changes apply to Firefox 156 and Firefox ESR 153.3.0 unless explicitly stated. Firefox ESR 153 is the current ESR.

Changes

  • FirefoxHome: Added a Widgets option to turn the new tab widgets on or off with Enabled, and to block individual widgets by ID with Blocked. (bug 1980406)
  • SitePolicies: Added a DisableServiceWorkers option to stop specific sites from registering or using service workers. Firefox 156 only. (bug 2045811)
  • DisableLaunchOnLogin: Now applies on macOS as well as Windows, following the macOS launch on login implementation. Does not apply to the ESR. (bug 2053447)

Fixes

Firefox 155

These changes apply to Firefox 155 and Firefox ESR 153.2.0 unless explicitly stated. Firefox ESR 153 is the current ESR.

New in Firefox 155

  • DisableLaunchOnLogin: This policy prevents Firefox from launching automatically when the user logs in (Windows only in 155). Does not apply to the ESR. (bug 2001734)

Changes

  • SitePolicies: Added an HttpsOnly option to prevent specific sites from being loaded over HTTP. Firefox 155 only. (bug 2045980)
  • Captive portal and network connectivity checks now use firefox-portal-detection.com instead of detectportal.firefox.com. Network allowlists and proxy rules naming the old domain need updating. Firefox 155 only. (bug 2049252, bug 1898891)

Fixes

  • ExtensionSettings: In Firefox 154 and Firefox ESR 153.1.0, configurations that quoted booleans ("true") would break and an invalid entry discarded the whole policy. The validator is relaxed to accept quoted booleans again, and invalid entries are now individually skipped. (bug 2065965)
  • SearchEngines: Contextual search prompted users to install a search engine when PreventInstalls was true. Firefox 155 only. (bug 2055614)
  • Locking legacy preferences such as pref.general.disable_button.default_browser didn't disable the corresponding controls in Firefox Settings, following the Settings rewrite. (bug 2056928, bug 2055887)
  • Firefox reported that it could pin itself to the taskbar when Windows Group Policy blocked pinning. Firefox 155 only. (bug 2059920)

Known issues

  • Some sites may load slowly or fail to load on networks that block UDP. This can affect corporate networks where a proxy or firewall blocks QUIC as part of TLS inspection. To work around it, set network.http.happy_eyeballs_enabled to false with the Preferences policy. A fix is planned for the next dot release. Does not apply to the ESR. (bug 2063452)

Firefox 154

These changes apply to Firefox 154 and Firefox ESR 153.1.0 unless explicitly stated. Firefox ESR 153 is the current ESR.

Firefox moves from a four-week to a two-week release cycle beginning with Firefox 155. Bug fixes, updates and features reach users more quickly once they are ready to ship.

New in Firefox 154

Changes

  • SanitizeOnShutdown: Added an Exceptions option to configure sites whose data should not be cleared on shutdown. Firefox 154 only. (bug 2049937)

Fixes

  • SearchEngines: PreventInstalls did not prevent users from manually adding search engines in Settings or from the context menu. (bug 2052965)
  • The -width and -height command-line options did not correctly set the Firefox window size. Firefox 154 only. (bug 1635927)
  • Extended Protection (channel and service binding) for Windows SSPI authentication worked when using SPNEGO but not when using Kerberos directly. (bug 1179722)

Firefox 153

These changes apply to Firefox 153 and Firefox ESR 153 unless explicitly stated. Firefox ESR 153 is the new ESR - enterprise changes are no longer backported to Firefox ESR 140. Policies listed under Firefox ESR 153.0.0 became available to ESR admins for the first time in this release.

New in Firefox 153

Changes

  • Containers: Updated for the new container color palette. Existing color names are migrated to the new names automatically.
  • Cookies: Behavior and BehaviorPrivateBrowsing accept partition-foreign, the new name for the reject-tracker-and-partition-foreign cookie behavior. Configurations using the old name continue to work.
  • ExtensionSettings: Control extension host permissions using runtime_allowed_hosts and runtime_blocked_hosts, and control which permissions extensions may request using allowed_permissions.
  • Users can no longer change the host permissions of Manifest V3 extensions installed using force_installed.
  • ExtensionSettings: force_installed and normal_installed extensions can be installed directly from addons.mozilla.org when install_url is omitted.
  • Homepage: Added a NewTabOnRestore option to open the default start page or about:newtab after restoring a previous session.
  • ManagedBookmarks: Bookmarklets using javascript: URLs are now supported.
  • Automatically discovered printers are now listed after manually configured printers in the print destination list. (bug 1996569)
  • Firefox installed from a macOS .pkg package can now update without prompting for administrator credentials. (bug 1812480)

Fixes

New in Firefox ESR 153.0.0

Firefox 152

These changes apply to Firefox 152 unless explicitly stated. Firefox ESR 140.12.0 shipped the same day, but most of these changes were not backported to it.

Changes

  • DefaultSerialGuardSetting: Web Serial support is now disabled by default when Firefox is managed by enterprise policies.
  • ExtensionSettings: Force-installed extensions are now always updated automatically, regardless of the updates_disabled setting. (bug 2037243)
  • FirefoxHome: Allow configuration of the Weather experience. Also in Firefox ESR 140.12.0.
  • ManagedBookmarks: Allow specifying favicons directly for managed bookmarks.
  • Chatbot content is now available to extensions from content scripts. (bug 1980404)
  • Firefox now accepts TURN server responses whose XOR-MAPPED-ADDRESS does not match the ICE check, improving compatibility with some TURN server implementations. (bug 2034159)

Fixes

Firefox 151

These changes apply to Firefox 151 and Firefox ESR 140.11.0 unless explicitly stated. Firefox ESR 140 is the current ESR, and enterprise changes are no longer backported to Firefox ESR 128.

Firefox 153 will be the next ESR. As that transition approaches, fewer non-security fixes and policy changes will be backported to Firefox ESR 140. If you use the ESR, we recommend testing with Firefox Beta or Nightly to identify issues before Firefox ESR 153 ships.

New in Firefox 151

  • DefaultSerialGuardSetting: Control use of the Web Serial API. Does not apply to the ESR.
  • XSLTEnabled: Enable or disable support for the XSLTProcessor JavaScript API and the XSLT processing instruction. Does not apply to the ESR.

Changes

Fixes

  • DisableRemoteImprovements: The policy was not reflected correctly in preferences. Firefox 151 only.
  • Sites blocked by enterprise policy did not display the correct error message. Firefox 151 only.

Firefox 150

These changes apply to Firefox 150 and Firefox ESR 140.10.0 unless explicitly stated. Firefox ESR 140 is the current ESR.

New in Firefox 150

  • RelaunchRequired: Require Firefox to be relaunched within a given period and notify the user of the upcoming relaunch. Does not apply to the ESR.
  • SitePolicies: Fine-grained control over policies for specific sites. Does not apply to the ESR.

Changes

Fixes

  • Homepage: The policy was not working correctly in Firefox 149. Fixed in Firefox 149.0.2. Does not apply to the ESR.

Notes

  • Firefox ESR 115 support for Windows 7/8 and macOS 10.12, 10.13 and 10.14 is extended to August 2026.

Firefox 149

These changes apply to Firefox 149 and Firefox ESR 140.9.0 unless explicitly stated.

New in Firefox 149.0.2

  • AIControls: Configure AI controls. Does not apply to the ESR.
  • IPProtectionAvailable: Prevent the built-in VPN from being available to users. Does not apply to the ESR.

Firefox 148

These changes apply to Firefox 148 unless explicitly stated. Firefox ESR 140.8.0 shipped the same day, but these changes were not backported to it.

New in Firefox 148

Changes

  • GenerativeAI: Updated to cover PDF alt text generation and translations. (bug 2013938)
  • AI Controls settings now respect enterprise policy and locale or region restrictions. (bug 2005805)
  • Firefox now reports whether a profile is managed by enterprise policy, as policies.is_enterprise in the baseline telemetry ping. (bug 1997959)

Firefox 147

These changes apply to Firefox 147 and Firefox ESR 140.7.0 unless explicitly stated. Firefox ESR 140 is the current ESR, so enterprise changes are no longer backported to Firefox ESR 128.

Fixes

  • Private Window options were still available from the Firefox View tab when private browsing was disabled. (bug 2004669)
  • A performance regression affecting extension native messaging reached the ESR in Firefox ESR 140.7.0. In earlier Firefox 140-series builds, native messaging operations could experience significantly increased latency, affecting enterprise extensions that communicate with external processes. The release channel received this fix in Firefox 146. (bug 2002517)

Known issues

  • Using Trellix DLP Endpoint for Windows can cause crashes when dragging and dropping files. Set the security.sandbox.content.close-ksecdd-handle preference to false as a workaround.

Firefox 146

These changes apply to Firefox 146 and Firefox ESR 140.6.0 unless explicitly stated.

New in Firefox 146

  • BrowserDataBackup: Disable backup or restore of profile data. Does not apply to the ESR.

Changes

  • The version number, architecture and language were removed from the Windows uninstall registry key, improving compatibility with third-party tools. Does not apply to the ESR. (bug 1995769)
  • Firefox Labs can now be enabled regardless of the status of DisableTelemetry or DisableFirefoxStudies. Does not apply to the ESR. (bug 1972647)

Fixes

Firefox 145

These changes apply to Firefox 145 and Firefox ESR 140.5.0 unless explicitly stated.

Mozilla has introduced Firefox Support for Organizations, a support offering for enterprise deployments of Firefox.

New in Firefox 145

  • LocalNetworkAccess: Configure local network access security features. Does not apply to the ESR.

Changes

  • GenerativeAI: Added an option to enable or disable all generative AI features.
  • EnableTrackingProtection: BaselineExceptions and ConvenienceExceptions can now be set in strict mode. Does not apply to the ESR.

Fixes

Firefox 144

These changes apply to Firefox 144 and Firefox ESR 140.4.0 unless explicitly stated.

New in Firefox 144

  • GenerativeAI: Configure generative AI features. Chatbot is the only option that applies to the ESR.
  • VisualSearchEnabled: Enable or disable visual search. Does not apply to the ESR.

New in Firefox ESR 140.4.0

  • GenerativeAI: Configure generative AI features. Only the Chatbot option is available on the ESR.

Changes

  • Preferences: Allow setting the security.webauthn.always_allow_direct_attestation preference.

Fixes

  • Some print options were still shown when printing was disabled. (bug 1889569)
  • Windows Kerberos authentication with Extended Protection did not work with a SHA384 SSL certificate. (bug 1895277)

Notes

  • Firefox ESR 115 support for Windows 7/8 and macOS 10.12, 10.13 and 10.14 is extended to March 2026.

Firefox 143

These changes apply to Firefox 143 and Firefox ESR 140.3.0 unless explicitly stated.

Notes

  • Firefox ESR 128 goes out of support with this release. Firefox ESR 128 users are upgraded to Firefox ESR 140.