Milestones and key data for Firefox 147

Release Date	January 13, 2026
Release Owner	Ryan VanderMeulen
Corresponding ESR releases	140.7.0 · 115.32.0^?
Current Beta	147.0b2 ^{(50% rollout)}
Bugs fixed in Nightly	1765
Nightly cycle length	4 weeks
Beta cycle length	5 weeks
Release notes	Beta notes

Milestones
Deadline to request manual QA QA has been informed (via a Jira ticket) about features that require manual testing during the nightly and/or beta cycle. Feature technical documentation is also required to draft Test Plans and Test Cases.	November 7 5 weeks ago
Deadline to request accessibility engineering review Accessibility engineering review has been requested (using the `a11y-review` flag on Bugzilla) for new (or significantly redesigned) UI that requires assessment to determine whether it is accessible to people with disabilities.	November 7 5 weeks ago
Nightly starts The first day of the cycle is Merge Day. After merging mozilla-central to mozilla-beta, we bump the nightly version number on mozilla-central and a new development cycle starts for Firefox. A new Firefox Nightly is shipped every 12 hours.	November 10 4.5 weeks ago
Build ready for QA Features with a QA request are ready for testing to assess feature quality and provide a formal test report by the end of Week 2 of the nightly cycle.	November 21 3 weeks ago
QA Test Plan approval due The QA team appreciates an earlier sign-off from the project teams. The approval milestone will be the final deadline for any feature Test Plan sign-offs. No feedback/sign-off on QAs Feature Test Plan could result in misalignment on testing scope, incomplete test coverage and invalid bugs.	November 21 3 weeks ago
Soft Code Freeze starts Draft beta release notes We are nearing the end of the nightly cycle. Don't land new untested features. Risky changes should be avoided after 8:00 AM UTC until after the nightly version bump on Merge Day.	December 4 8 days ago
String Freeze starts In order to ensure that our localizers have adequate time to translate strings, please make sure that all string changes have landed by end of day.	December 5 7 days ago
QA pre-merge regression testing done QA assess build readiness for shipping to Beta by running a set of Regression test cases and shares a test report.	December 5 7 days ago
Merge day This is the day in the release cycle when we merge mozilla-central into mozilla-beta. This is the end of the development cycle for Firefox 147 and the beginning of our Beta stabilization cycle.	December 8 4 days ago
Beta 1 Go to build Built manually just after the merge. It ships on Tuesday. Uplift requests are open.	December 8 4 days ago
Beta 1 Rolled out to 25% of our beta population. Some experimental features are still activated to watch their behavior on a wider population. These experimental features will be deactivated mid-cycle.	December 9 3 days ago
Beta 2 First automated beta of the cycle. It is rolled out to 50% of our beta population. Build starts at 13:00 UTC. Stabilization work via uplifts.	December 10 2 days ago
Beta 3 Beta rollout bumped to 100% provided stability is good. Build starts at 13:00 UTC. Stabilization work via uplifts.	December 12 Today
SUMO content creation User affecting changes were identified and provided to the support.mozilla.org team. The support content for this release can now be created and will be translated before RC week.	December 12 Today
Beta 4 Build starts at 13:00 UTC. Stabilization work via uplifts.	December 15 No working day before milestone
Beta 5 Build starts at 13:00 UTC. Stabilization work via uplifts.	December 17 In 2 working days
Beta 6 Last early beta On a regular 4 weeks beta cycle, Beta 6 is the last beta with experimental features still activated. Build starts at 13:00 UTC. Stabilization work via uplifts.	December 19 In 4 working days
Beta 7 Experimental features are no longer activated at compile time. Build starts at 13:00 UTC. Stabilization work via uplifts.	December 22 In 5 working days
SUMO content localization New content on support.mozilla.org team is finalized, uploaded to the server and provided to our localization teams internationally.	December 22 In 5 working days
Beta 8 Last week of the beta cycle. Build starts at 13:00 UTC. Stabilization work via uplifts.	December 29 In 2 weeks
Pre-release QA sign-off A week before the final sign-off, QA shares preliminary test reports for each feature riding the train. This pre-release sign-off can be Green, Yellow or Red.	December 29 In 2 weeks
Beta 9 Last beta uplifts (sec-approval request deadline) On a regular 4 weeks beta cycle, this is the last beta and thus the end of beta uplifts, including security bugs for this release (`sec-approval+` on Bugzilla). Build starts at 13:00 UTC.	December 31 In 2.5 weeks
Release Candidate Go to build We merge our mozilla-beta repository to mozilla-release and close mozilla-beta until the next merge day. We then build our Release Candidate from mozilla-release. This is the build we intend to ship a week later unless we need to build another Release Candidate to fix a major quality or business critical issue.	January 5 In 3 weeks
Release Candidate Release notes finalized Our Release Candidate is shipped to all of our beta population.	January 6 In 3 weeks
Release day! We ship Firefox 147 at 14:00 UTC (6AM PST) at 25% rollout.	January 13 In 4 weeks
Potential Android dot release One week after the release, we evaluate shipping an Android dot release to address identified issues. We can also enable new features on a on a case by case basis if they are suitable for uplift. The decision on shipping or not this dot release for Android is on the release management team.	January 20 In 5 weeks
Planned dot release Two weeks after the release, we ship a desktop and/or an Android dot release to address identified quality issues with safe fixes ready. We can also enable new features on a on a case by case basis if they are suitable for uplift. We may have to ship other dot releases before that date. If this is the case and post-release quality issues are already fixed and shipped, the decision on shipping or not the planned dot release is on the release management team.	January 27 In 6 weeks

Milestones
147.0 branch is created The `firefox-v147.0` branch is created from the `main` branch. `version.txt` is bumped to 147.1 on `main`. Any further code change for the 147.0 release now requires an uplift request.	December 29
147.0 release candidate is created The 147.0 release candidate is created based on the `firefox-v147.0` branch. This build might contain additional uplifts. Additionaly, the 146.3 release is tagged as shipped.	December 29
Preliminary QA sign off on 147.0 QA gives a preliminary sign off on 147.0. If it is green, we push the build to the External Beta Testers group. Otherwise, the dev team fixes the issues reported by QA, uplift them to the release branch and we build another Release Candidate.	December 29
Final QA sign off on 147.0 Release notes ready QA gives its final sign off on 147.0. If the sign off is red, the dev team fixes the issues reported by QA, uplift them to the release branch and we build another Release Candidate.	December 30
147.0 sent to Apple Store We submit 147.0 for review to the Apple Store. If we don`t have a working build by the end of the day, we may not ship this week.	January 8
147.1 branch is created The `firefox-v147.1` branch is created from the `main` branch. `version.txt` is bumped to 147.2 on `main`. Any further code change for the 147.1 release now requires an uplift request.	January 9
147.1 release candidate is created The 147.1 release candidate is created based on the `firefox-v147.0` branch. This build might contain additional uplifts. Additionaly, the 147.0 release is tagged as shipped.	January 9
147.0 is shipped 147.0 is shipped on the Apple Store at 3:00 AM UTC with a phased 7 days rollout: Monday: 1%, Tuesday: 2%, Wednesday: 5%, Thursday: 10%, Friday: 20%, Saturday: 50%, Sunday: 100%.	January 12
Preliminary QA sign off on 147.1 QA gives a preliminary sign off on 147.1. If it is green, we push the build to the External Beta Testers group. Otherwise, the dev team fixes the issues reported by QA, uplift them to the release branch and we build another Release Candidate.	January 12
Final QA sign off on 147.1 Release notes ready QA gives its final sign off on 147.1. If the sign off is red, the dev team fixes the issues reported by QA, uplift them to the release branch and we build another Release Candidate.	January 13
147.1 sent to Apple Store We submit 147.1 for review to the Apple Store. If we don`t have a working build by the end of the day, we may not ship this week.	January 15
147.2 branch is created The `firefox-v147.2` branch is created from the `main` branch. `version.txt` is bumped to 147.3 on `main`. Any further code change for the 147.2 release now requires an uplift request.	January 16
147.2 release candidate is created The 147.2 release candidate is created based on the `firefox-v147.0` branch. This build might contain additional uplifts. Additionaly, the 147.1 release is tagged as shipped.	January 16
147.1 is shipped 147.1 is shipped on the Apple Store at 3:00 AM UTC with a phased 7 days rollout: Monday: 1%, Tuesday: 2%, Wednesday: 5%, Thursday: 10%, Friday: 20%, Saturday: 50%, Sunday: 100%.	January 19
Preliminary QA sign off on 147.2 QA gives a preliminary sign off on 147.2. If it is green, we push the build to the External Beta Testers group. Otherwise, the dev team fixes the issues reported by QA, uplift them to the release branch and we build another Release Candidate.	January 19
Final QA sign off on 147.2 Release notes ready QA gives its final sign off on 147.2. If the sign off is red, the dev team fixes the issues reported by QA, uplift them to the release branch and we build another Release Candidate.	January 20
147.2 sent to Apple Store We submit 147.2 for review to the Apple Store. If we don`t have a working build by the end of the day, we may not ship this week.	January 22
147.3 branch is created The `firefox-v147.3` branch is created from the `main` branch. `version.txt` is bumped to 147.4 on `main`. Any further code change for the 147.3 release now requires an uplift request.	January 23
147.3 release candidate is created The 147.3 release candidate is created based on the `firefox-v147.0` branch. This build might contain additional uplifts. Additionaly, the 147.2 release is tagged as shipped.	January 23
147.2 is shipped 147.2 is shipped on the Apple Store at 3:00 AM UTC with a phased 7 days rollout: Monday: 1%, Tuesday: 2%, Wednesday: 5%, Thursday: 10%, Friday: 20%, Saturday: 50%, Sunday: 100%.	January 26
Preliminary QA sign off on 147.3 QA gives a preliminary sign off on 147.3. If it is green, we push the build to the External Beta Testers group. Otherwise, the dev team fixes the issues reported by QA, uplift them to the release branch and we build another Release Candidate.	January 26
Final QA sign off on 147.3 Release notes ready QA gives its final sign off on 147.3. If the sign off is red, the dev team fixes the issues reported by QA, uplift them to the release branch and we build another Release Candidate.	January 27
147.3 sent to Apple Store We submit 147.3 for review to the Apple Store. If we don`t have a working build by the end of the day, we may not ship this week.	January 29
147.4 branch is created The `firefox-v147.4` branch is created from the `main` branch. `version.txt` is bumped to 147.5 on `main`. Any further code change for the 147.4 release now requires an uplift request.	January 30
147.4 release candidate is created The 147.4 release candidate is created based on the `firefox-v147.0` branch. This build might contain additional uplifts. Additionaly, the 147.3 release is tagged as shipped.	January 30
147.3 is shipped 147.3 is shipped on the Apple Store at 3:00 AM UTC with a phased 7 days rollout: Monday: 1%, Tuesday: 2%, Wednesday: 5%, Thursday: 10%, Friday: 20%, Saturday: 50%, Sunday: 100%.	February 2
Preliminary QA sign off on 147.4 QA gives a preliminary sign off on 147.4. If it is green, we push the build to the External Beta Testers group. Otherwise, the dev team fixes the issues reported by QA, uplift them to the release branch and we build another Release Candidate.	February 2
Final QA sign off on 147.4 Release notes ready QA gives its final sign off on 147.4. If the sign off is red, the dev team fixes the issues reported by QA, uplift them to the release branch and we build another Release Candidate.	February 3
147.4 sent to Apple Store We submit 147.4 for review to the Apple Store. If we don`t have a working build by the end of the day, we may not ship this week.	February 5
147.5 branch is created The `firefox-v147.5` branch is created from the `main` branch. `version.txt` is bumped to 148.0 on `main`. Any further code change for the 147.5 release now requires an uplift request.	February 6
147.5 release candidate is created The 147.5 release candidate is created based on the `firefox-v147.0` branch. This build might contain additional uplifts. Additionaly, the 147.4 release is tagged as shipped.	February 6
147.4 is shipped 147.4 is shipped on the Apple Store at 3:00 AM UTC with a phased 7 days rollout: Monday: 1%, Tuesday: 2%, Wednesday: 5%, Thursday: 10%, Friday: 20%, Saturday: 50%, Sunday: 100%.	February 9
Preliminary QA sign off on 147.5 QA gives a preliminary sign off on 147.5. If it is green, we push the build to the External Beta Testers group. Otherwise, the dev team fixes the issues reported by QA, uplift them to the release branch and we build another Release Candidate.	February 9
Final QA sign off on 147.5 Release notes ready QA gives its final sign off on 147.5. If the sign off is red, the dev team fixes the issues reported by QA, uplift them to the release branch and we build another Release Candidate.	February 10
147.5 sent to Apple Store We submit 147.5 for review to the Apple Store. If we don`t have a working build by the end of the day, we may not ship this week.	February 12
147.5 is shipped 147.5 is shipped on the Apple Store at 3:00 AM UTC with a phased 7 days rollout: Monday: 1%, Tuesday: 2%, Wednesday: 5%, Thursday: 10%, Friday: 20%, Saturday: 50%, Sunday: 100%.	February 16