Milestones and key data for Firefox 149

Release Date	March 24, 2026
Release Owner	Pascal Chevrel
Corresponding ESR releases	140.9.0
Latest BuildID	20260223091613
Nightly cycle length	6 weeks
Beta cycle length	4 weeks
Release notes	Nightly notes

Milestones
Deadline to request manual QA QA has been informed via a Jira ticket (Functional, Nimbus/Remote delivery or Embedded QA) about features needing manual testing — more on how to file a Jira ticket here. Test Plans and Cases also require the technical documentation, which should be attached to the ticket.	January 9 6 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.	January 9 6 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.	January 12 6 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.	February 6 2 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.	February 6 2 weeks ago
Draft beta release notes A draft document was created and shared internally with stakeholders to prepare our final release notes for general availability. This document initially contains a copy of our public beta release notes shipping the week after and will be enriched during the beta cycle with media and final copy.	February 18 5 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.	February 20 3 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.	February 20 3 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 149 and the beginning of our Beta stabilization cycle.	February 23 Today
Beta 1 Rolled out to 50% 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.	February 25 1 working day
Beta 2 First automated beta of the cycle. It is rolled out to 100% of our beta population. Build starts at 13:00 UTC. Stabilization work via uplifts.	February 27 In 3 working days
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.	February 27 In 3 working days
Beta 3 Build starts at 13:00 UTC. Stabilization work via uplifts.	March 2 In 4 working days
Beta 4 Build starts at 13:00 UTC. Stabilization work via uplifts.	March 4 In 6 working days
Beta 5 Last early beta On a regular 4 weeks beta cycle, Beta 5 is the last beta with experimental features still activated. Build starts at 13:00 UTC. Stabilization work via uplifts.	March 6^? In 8 working days
Beta 6 Build starts at 13:00 UTC. Stabilization work via uplifts. Experimental features are no longer activated at compile time.	March 9 In 8 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.	March 9 In 8 working days
Beta 7 Build starts at 13:00 UTC. Stabilization work via uplifts.	March 11 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.	March 11 In 2 weeks
Beta 8 Security bugs uplift request deadline Build starts at 13:00 UTC. Stabilization work via uplifts. Last security bugs uplifts for this release (`sec-approval+` on Bugzilla).	March 13 In 2 weeks
Beta 9 Build starts at 13:00 UTC. Stabilization work via uplifts.	March 16 In 2.5 weeks
Release notes submission deadline All release notes for Firefox were added to the draft document or communicated directly with the release manager. Illustrations such as screenshots and videos were provided. Final Release release notes are created by the release manager on firefox.com.	March 17 In 3 weeks
Beta 10 Last beta uplifts On a regular 4 weeks beta cycle, this is the last beta and thus the end of beta uplifts. Build starts at 13:00 UTC.	March 18 In 3 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.	March 18 In 3 weeks
Release Candidate Release notes finalized Our Release Candidate is built and available for testing.	March 18 In 3 weeks
Release day! We ship Firefox 149 at 14:00 UTC (6AM PST) at 25% rollout.	March 24 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.	March 31 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.	April 7 In 6 weeks

Milestones
149.0 branch is created The `firefox-v149.0` branch is created from the `main` branch. `version.txt` is bumped to 149.1 on `main`. Any further code change for the 149.0 release now requires an uplift request.	March 13
149.0 release candidate is created The 149.0 release candidate is created based on the `firefox-v149.0` branch. This build might contain additional uplifts. Additionaly, the 148.3 release is tagged as shipped.	March 13
Preliminary QA sign off on 149.0 QA gives a preliminary sign off on 149.0. 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.	March 16
Final QA sign off on 149.0 Release notes ready QA gives its final sign off on 149.0. 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.	March 17
149.0 sent to Apple Store We submit 149.0 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.	March 17
149.1 branch is created The `firefox-v149.1` branch is created from the `main` branch. `version.txt` is bumped to 149.2 on `main`. Any further code change for the 149.1 release now requires an uplift request.	March 20
149.1 release candidate is created The 149.1 release candidate is created based on the `firefox-v149.0` branch. This build might contain additional uplifts. Additionaly, the 149.0 release is tagged as shipped.	March 20
149.0 is shipped 149.0 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%.	March 23
Preliminary QA sign off on 149.1 QA gives a preliminary sign off on 149.1. 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.	March 23
Final QA sign off on 149.1 Release notes ready QA gives its final sign off on 149.1. 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.	March 24
149.1 sent to Apple Store We submit 149.1 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.	March 26
149.2 branch is created The `firefox-v149.2` branch is created from the `main` branch. `version.txt` is bumped to 149.3 on `main`. Any further code change for the 149.2 release now requires an uplift request.	March 27
149.2 release candidate is created The 149.2 release candidate is created based on the `firefox-v149.0` branch. This build might contain additional uplifts. Additionaly, the 149.1 release is tagged as shipped.	March 27
149.1 is shipped 149.1 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%.	March 30
Preliminary QA sign off on 149.2 QA gives a preliminary sign off on 149.2. 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.	March 30
Final QA sign off on 149.2 Release notes ready QA gives its final sign off on 149.2. 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.	March 31
149.2 sent to Apple Store We submit 149.2 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.	April 2
149.3 branch is created The `firefox-v149.3` branch is created from the `main` branch. `version.txt` is bumped to 150.0 on `main`. Any further code change for the 149.3 release now requires an uplift request.	April 3
149.3 release candidate is created The 149.3 release candidate is created based on the `firefox-v149.0` branch. This build might contain additional uplifts. Additionaly, the 149.2 release is tagged as shipped.	April 3
149.2 is shipped 149.2 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%.	April 6
Preliminary QA sign off on 149.3 QA gives a preliminary sign off on 149.3. 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.	April 6
Final QA sign off on 149.3 Release notes ready QA gives its final sign off on 149.3. 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.	April 7
149.3 sent to Apple Store We submit 149.3 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.	April 9
149.3 is shipped 149.3 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%.	April 13