Except where noted, everything here applies to both Firefox 137 and the Firefox 128.9 ESR.

Other Changes

• An internal change has been made to Firefox that removes XPCOMUtils.defineLazyGetter. For most people, this shouldn't matter, but if you encounter problems with AutoConfig or third party software like PolicyPak, this might be the cause. You'll need to reach out to your provider. This does not apply to the ESR.

Special Notes

Firefox ESR 140

Firefox 140 is the next ESR and will be released on June 24, 2025.