Except where noted, everything here applies only to Firefox 140. Firefox 140 is the next ESR so, going forward, no enterprise changes will be backported to Firefox 128 ESR.

Bug Fixes

• Previously, access to about:debugging was completely removed if you didn't allow the installation of addons. Now we just disable the Load Temporary Add-on… button. This was fixed in bug 1778559.

Policies

• The DisableBuiltinPDFViewer policy no longer completely disables PDF.js; it changes the handler to send PDF files to the operating system. Embedded PDF files are shown in the browser. If you need to completely disable PDF.js, you can use the PDFjs policy.
• With the shutdown of Pocket, all Pocket related policies have been deprecated.

Special Notes

There are two more planned releases of Firefox 128 ESR, and then it will go out of support on September 16, 2025. Users will then be automatically upgraded to Firefox 140 ESR.

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