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Release DateFebruary 24, 2026
Release OwnerDonal Meehan
Corresponding ESR releases 140.8.0 · 115.33.0?
Latest BuildID 20251208220232
Nightly cycle length5 weeks
Beta cycle length6 weeks
Release notes Nightly 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.

December 5
4 days 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.

December 5
4 days 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.

December 8
Yesterday
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.

December 19
In 7 working days
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.

December 19
In 7 working days
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.

January 8
In 4 weeks
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.

January 9
In 4 weeks
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.

January 9
In 4 weeks
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 148 and the beginning of our Beta stabilization cycle.

January 12
In 4.5 weeks
Beta 1 Go to build

Built manually just after the merge. It ships on Tuesday. Uplift requests are open.

January 12
In 4.5 weeks
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.

January 13
In 4.5 weeks
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.

January 14
In 5 weeks
Beta 3

Beta rollout bumped to 100% provided stability is good. Build starts at 13:00 UTC. Stabilization work via uplifts.

January 16
In 5 weeks
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.

January 16
In 5 weeks
Beta 4

Build starts at 13:00 UTC. Stabilization work via uplifts.

January 19
In 5.5 weeks
Beta 5

Build starts at 13:00 UTC. Stabilization work via uplifts.

January 21
In 6 weeks
Beta 6

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.

January 23
In 6 weeks
Beta 7

Experimental features are no longer activated at compile time. Build starts at 13:00 UTC. Stabilization work via uplifts.

January 26
In 6.5 weeks
SUMO content localization

New content on support.mozilla.org team is finalized, uploaded to the server and provided to our localization teams internationally.

January 26
In 6.5 weeks
Beta 8

Last week of the beta cycle. Build starts at 13:00 UTC. Stabilization work via uplifts.

January 28
In 7 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.

January 28
In 7 weeks
Beta 9 Last early beta

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.

January 30
In 7 weeks
Beta 10

Extra beta usually due to a longer beta cycle. Build starts at 13:00 UTC. Stabilization work via uplifts.

February 2
In 7.5 weeks
Beta 11

Extra beta usually due to a longer beta cycle. Build starts at 13:00 UTC. Stabilization work via uplifts.

February 4
In 8 weeks
Beta 12

Extra beta usually due to a longer beta cycle. Build starts at 13:00 UTC. Stabilization work via uplifts.

February 6
In 8 weeks
Beta 13

Extra beta usually due to a longer beta cycle. Build starts at 13:00 UTC. Stabilization work via uplifts.

February 9
In 8.5 weeks
Beta 14

Extra beta usually due to a longer beta cycle. Build starts at 13:00 UTC. Stabilization work via uplifts.

February 11
In 9 weeks
Beta 15 Last beta uplifts (sec-approval request deadline)

Extra beta usually due to a longer beta cycle. Build starts at 13:00 UTC. Stabilization work via uplifts.

February 13
In 9 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.

February 16
In 9.5 weeks
Release Candidate Release notes finalized

Our Release Candidate is shipped to all of our beta population.

February 17
In 9.5 weeks
Release day!

We ship Firefox 148 at 14:00 UTC (6AM PST) at 25% rollout.

February 24
In 10.5 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 3
In 11.5 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.

March 10
In 12.5 weeks
Milestones
148.0 branch is created

The firefox-v148.0 branch is created from the main branch. version.txt is bumped to 148.1 on main. Any further code change for the 148.0 release now requires an uplift request.

February 13
148.0 release candidate is created

The 148.0 release candidate is created based on the firefox-v148.0 branch. This build might contain additional uplifts. Additionaly, the 147.3 release is tagged as shipped.

February 13
Preliminary QA sign off on 148.0

QA gives a preliminary sign off on 148.0. 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.

February 16
Final QA sign off on 148.0 Release notes ready

QA gives its final sign off on 148.0. 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.

February 17
148.0 sent to Apple Store

We submit 148.0 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.

February 19
148.1 branch is created

The firefox-v148.1 branch is created from the main branch. version.txt is bumped to 148.2 on main. Any further code change for the 148.1 release now requires an uplift request.

February 20
148.1 release candidate is created

The 148.1 release candidate is created based on the firefox-v148.0 branch. This build might contain additional uplifts. Additionaly, the 148.0 release is tagged as shipped.

February 20
148.0 is shipped

148.0 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%.

February 23
Preliminary QA sign off on 148.1

QA gives a preliminary sign off on 148.1. 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.

February 23
Final QA sign off on 148.1 Release notes ready

QA gives its final sign off on 148.1. 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.

February 24
148.1 sent to Apple Store

We submit 148.1 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.

February 26
148.2 branch is created

The firefox-v148.2 branch is created from the main branch. version.txt is bumped to 148.3 on main. Any further code change for the 148.2 release now requires an uplift request.

February 27
148.2 release candidate is created

The 148.2 release candidate is created based on the firefox-v148.0 branch. This build might contain additional uplifts. Additionaly, the 148.1 release is tagged as shipped.

February 27
148.1 is shipped

148.1 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 2
Preliminary QA sign off on 148.2

QA gives a preliminary sign off on 148.2. 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 2
Final QA sign off on 148.2 Release notes ready

QA gives its final sign off on 148.2. 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 3
148.2 sent to Apple Store

We submit 148.2 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.

March 5
148.3 branch is created

The firefox-v148.3 branch is created from the main branch. version.txt is bumped to 149.0 on main. Any further code change for the 148.3 release now requires an uplift request.

March 5
148.3 release candidate is created

The 148.3 release candidate is created based on the firefox-v148.0 branch. This build might contain additional uplifts. Additionaly, the 148.2 release is tagged as shipped.

March 5
148.2 is shipped

148.2 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%.

March 9
Preliminary QA sign off on 148.3

QA gives a preliminary sign off on 148.3. 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.

March 9
Final QA sign off on 148.3 Release notes ready

QA gives its final sign off on 148.3. 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.

March 10
148.3 sent to Apple Store

We submit 148.3 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.

March 12
148.3 is shipped

148.3 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%.

March 16