Milestones and key data for Firefox 152

Release Date	June 16, 2026
Release Owner	Donal Meehan
Corresponding ESR releases	140.12.0
Nightly cycle length	4 weeks
Beta cycle length	4 weeks

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.	April 17 In 17.5 weeks
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.	April 17 In 17.5 weeks
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.	April 20 In 18 weeks
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.	May 1 In 19.5 weeks
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.	May 1 In 19.5 weeks
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.	May 14 In 21.5 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.	May 15 In 21.5 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.	May 15 In 21.5 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 152 and the beginning of our Beta stabilization cycle.	May 18 In 22 weeks
Beta 1 Go to build Built manually just after the merge. It ships on Tuesday. Uplift requests are open.	May 18 In 22 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.	May 19 In 22 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.	May 20 In 22.5 weeks
Beta 3 Beta rollout bumped to 100% provided stability is good. Build starts at 13:00 UTC. Stabilization work via uplifts.	May 22 In 22.5 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.	May 22 In 22.5 weeks
Beta 4 Build starts at 13:00 UTC. Stabilization work via uplifts.	May 25 In 23 weeks
Beta 5 Build starts at 13:00 UTC. Stabilization work via uplifts.	May 27 In 23.5 weeks
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.	May 29 In 23.5 weeks
Beta 7 Experimental features are no longer activated at compile time. Build starts at 13:00 UTC. Stabilization work via uplifts.	June 1 In 24 weeks
SUMO content localization New content on support.mozilla.org team is finalized, uploaded to the server and provided to our localization teams internationally.	June 1 In 24 weeks
Beta 8 Last week of the beta cycle. Build starts at 13:00 UTC. Stabilization work via uplifts.	June 3 In 24.5 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.	June 3 In 24.5 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.	June 5^? In 24.5 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.	June 8 In 25 weeks
Release Candidate Release notes finalized Our Release Candidate is shipped to all of our beta population.	June 9 In 25 weeks
Release day! We ship Firefox 152 at 14:00 UTC (6AM PST) at 25% rollout.	June 16 In 26 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.	June 23 In 27 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.	June 30 In 28 weeks

Milestones
152.0 branch is created The `firefox-v152.0` branch is created from the `main` branch. `version.txt` is bumped to 152.1 on `main`. Any further code change for the 152.0 release now requires an uplift request.	June 4
152.0 release candidate is created The 152.0 release candidate is created based on the `firefox-v152.0` branch. This build might contain additional uplifts. Additionaly, the 151.3 release is tagged as shipped.	June 4
Preliminary QA sign off on 152.0 QA gives a preliminary sign off on 152.0. 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.	June 8
Final QA sign off on 152.0 Release notes ready QA gives its final sign off on 152.0. 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.	June 9
152.0 sent to Apple Store We submit 152.0 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.	June 9
152.1 branch is created The `firefox-v152.1` branch is created from the `main` branch. `version.txt` is bumped to 152.2 on `main`. Any further code change for the 152.1 release now requires an uplift request.	June 12
152.1 release candidate is created The 152.1 release candidate is created based on the `firefox-v152.0` branch. This build might contain additional uplifts. Additionaly, the 152.0 release is tagged as shipped.	June 12
152.0 is shipped 152.0 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%.	June 15
Preliminary QA sign off on 152.1 QA gives a preliminary sign off on 152.1. 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.	June 15
Final QA sign off on 152.1 Release notes ready QA gives its final sign off on 152.1. 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.	June 16
152.1 sent to Apple Store We submit 152.1 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.	June 18
152.2 branch is created The `firefox-v152.2` branch is created from the `main` branch. `version.txt` is bumped to 152.3 on `main`. Any further code change for the 152.2 release now requires an uplift request.	June 19
152.2 release candidate is created The 152.2 release candidate is created based on the `firefox-v152.0` branch. This build might contain additional uplifts. Additionaly, the 152.1 release is tagged as shipped.	June 19
152.1 is shipped 152.1 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%.	June 22
Preliminary QA sign off on 152.2 QA gives a preliminary sign off on 152.2. 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.	June 22
Final QA sign off on 152.2 Release notes ready QA gives its final sign off on 152.2. 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.	June 23
152.2 sent to Apple Store We submit 152.2 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.	June 25
152.3 branch is created The `firefox-v152.3` branch is created from the `main` branch. `version.txt` is bumped to 152.4 on `main`. Any further code change for the 152.3 release now requires an uplift request.	June 26
152.3 release candidate is created The 152.3 release candidate is created based on the `firefox-v152.0` branch. This build might contain additional uplifts. Additionaly, the 152.2 release is tagged as shipped.	June 26
152.2 is shipped 152.2 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%.	June 29
Preliminary QA sign off on 152.3 QA gives a preliminary sign off on 152.3. 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.	June 29
Final QA sign off on 152.3 Release notes ready QA gives its final sign off on 152.3. 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.	June 30
152.3 sent to Apple Store We submit 152.3 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.	July 2
152.4 branch is created The `firefox-v152.3` branch is created from the `main` branch. `version.txt` is bumped to 153.0 on `main`. Any further code change for the 152.3 release now requires an uplift request.	July 3
152.4 release candidate is created The 152.4 release candidate is created based on the `firefox-v152.0` branch. This build might contain additional uplifts. Additionaly, the 152.3 release is tagged as shipped.	July 3
152.3 is shipped 152.3 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%.	July 6
Preliminary QA sign off on 152.4 QA gives a preliminary sign off on 152.4. 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.	July 6
Final QA sign off on 152.4 Release notes ready QA gives its final sign off on 152.4. 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.	July 7
152.4 sent to Apple Store We submit 152.4 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.	July 9
152.4 is shipped 152.4 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%.	July 13