Except where noted, everything here applies to both Firefox 139 and the Firefox 128.11 ESR.

Other Changes

• Extensions installed via policy can now enable or disable other extensions. This was fixed in bug 1966113.

Policies

• The SearchEngines policy is now available on all versions of Firefox (not just the ESR).

Special Notes

Firefox ESR 140

Firefox 140 is the next ESR and will be released on June 24, 2025. Going forward, we will only be backporting security fixes to the Firefox 128 ESR.

If you use the ESR, we strongly recommend that you start testing with Firefox Beta to see if there are any issues you have with the new ESR.

If you need to prevent upgrades for any reason, you can use the AppUpdatePin policy.