A maintenance release of Firefox 147.0.1 is available, which includes three fixes:
- The “Compression Dictionary Transport” mechanism added in release 147 has been temporarily disabled due to compatibility problems with some sites that use this technology. For example, issues have been reported with the ChatGPT site. To enable support for content compression using dictionaries sent by the server, users can adjust the “network.http.dictionaries.enable” setting on the about:config page.
- A bug in the implementation of Freedesktop.org XDG Base Directory specifications has been fixed. Despite the transfer of storage of profiles, add-ons, settings, and internal databases to directory “~/.config/mozilla”, the browser was creating an empty directory “~/.mozilla/extensions”.
- An issue with determining the time format in the Intl.DateTimeFormat method has been resolved. This problem was causing incorrect time display on some sites.
Additionally, it has been announced that support for the old sidebar in Firefox will be discontinued this year. A new implementation of the sidebar was introduced in Firefox 136, featuring a collapsed form that displays only buttons for available operations. In newer builds of Firefox, the new panel is enabled by default. Users of the old panel will be automatically transitioned to the new panel in the second quarter of 2026, with an option to revert to the old panel. By the third quarter of 2026, the code for the old panel and the option to switch back will be removed from Firefox.
/Reports, release notes, official announcements.