Firefox Development Completes Transition from Mercurial to Git on GitHub After 1.5 Years

The developers of the Firefox Development team have successfully completed the migration process after a year and a half since the beginning of the migration. They announced that the Firefox Desktop browser project has fully transitioned from the cross-platform distributed version control system Mercurial to Git, with the project now hosted on GitHub. Changes can now be submitted via pull requests through this repository.

In November 2023, the project team clarified that, for an extended period, Firefox development was supporting both Mercurial and Git, which placed a significant burden on developers. To streamline the project and focus on more relevant tools, Firefox Development opted to switch the development to Git.

During the migration, the Firefox Development team undertook preparatory work with developers, including changing the primary repository from Mercurial to Git and removing Mercurial support from developers’ workstations. They then initiated a phased migration of the server infrastructure. While the migration was expected to take about six months, it ultimately took a year and a half to complete.

Some individual Mercurial repositories have been consolidated into a single Git space and are now accessible through Git branches: the mozilla-central repository is now the main branch in the Firefox Git repository, mozilla-beta is the beta branch, mozilla-release is the release branch, mozilla-esr115 is the esr-115 branch, mozilla-esr-128 is the esr-128 branch, and autoland is the autoland branch. Services such as Bugzilla, moz-phab, Phabricator, and Lando will continue to operate unchanged. The old Mercurial repositories are still available but have been switched to synchronized mirror mode.