The upcoming Firefox 147 will introduce a long-requested change for Linux users by finally adopting the XDG Base Directory Specification, closing a bug that has been open for more than 21 years.
The update modernizes how the browser stores files on Linux systems and aligns its behavior with that of most desktop applications, which have been doing so for years. Here’s what I’m talking about.
Until now, Firefox placed nearly all of its user files—settings, profiles, data, and cache—inside a single folder called ~/.mozilla in the user’s home directory. This approach worked, but it also contributed to the familiar clutter many Linux users see when applications each create their own hidden folders.
At the same time, the XDG Base Directory Specification is a widely used standard that aims to organize those files cleanly. Instead of placing everything directly in a single directory, applications are encouraged to use three dedicated locations: one for configuration files, one for application data, and one for cache files. These are typically found under ~/.config, ~/.local/share, and ~/.cache.
Starting with Firefox 147, newly created profiles on Linux will follow this structure. Configuration files, long-term data, and temporary cache files will now be stored in their proper locations.
It’s important to note that this doesn’t affect existing users immediately: if a legacy ~/.mozilla folder already exists, Firefox keeps using it to avoid breaking profiles. But for anyone installing Firefox fresh or creating new profiles, the browser will behave like other modern Linux applications.
As I said in the beginning, the change also marks the end of one of the browser’s longest-standing issues. Believe it or not, bug 259356 was first reported in 2003, and the request to support XDG directories has resurfaced repeatedly among Linux users and distributions over the years.
It is expected that this change will finally simplify file management, reduce home-folder clutter, and, most importantly, align the browser with the expectations of today’s Linux environments.
So basically I will never notice any difference.