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Release DateSeptember 21, 2027
Release OwnerPascal Chevrel
Corresponding ESR releases 175.6.0
Nightly cycle length2 weeks
Beta cycle length2 weeks
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.

August 12
In 42 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.

August 19
In 43 weeks
Nightly starts

The first day of the cycle is Merge Day. After merging firefox-main to the beta branch, we bump the nightly version number on firefox-main and a new development cycle starts for Firefox. A new Firefox Nightly is shipped every 12 hours.

August 19
In 43 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.

August 26
In 44 weeks
QA Test Case review

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.

August 27
In 44 weeks
Strings hand-off to engineering

Final strings are handed off to Engineering to ensure they are landed before localization begins.

August 30
In 44.5 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.

September 1
In 44.5 weeks
Nightly QA sign-off

QA signs off on new features in Nightly by sharing individual test reports with their quality assessment and reasoning.

September 1
In 44.5 weeks
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.

September 2
In 45 weeks
Merge day

This is the day in the release cycle when we merge firefox-main into the beta branch. This is the end of the development cycle for Firefox 181 and the beginning of our Beta stabilization cycle.

September 2
In 45 weeks
Beta 1

First beta of the cycle, rolled out to our beta population. Build starts at 13:00 UTC. Stabilization work via uplifts.

September 6
In 45.5 weeks
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.

September 8
In 45.5 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 before release day.

September 9
In 46 weeks
Beta 3

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

September 10
In 46 weeks
Beta 4

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

September 13
In 46.5 weeks
Deadline to request security bug uplifts ESR patches must be ready

Deadline for security bugs uplift requests (sec-approval+ on Bugzilla).
ESR releases go to build on this day, before the last beta and the Release Candidate. Patches for security bugs affecting ESR branches must therefore be ready by this deadline.

September 14
In 46.5 weeks
Beta 5 Last beta uplifts

Last beta of the cycle and thus the end of beta uplifts. Build starts at 13:00 UTC.
After beta 5, we merge the beta branch to the release branch and close beta until the next merge day. We then build our Release Candidate from release.

September 15
In 46.5 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.

September 16
In 47 weeks
Release Candidate Ready for QA

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.

September 16
In 47 weeks
Release day!

Firefox 181 ships at 13:00 UTC (6 AM PT) with an initial 25% rollout.

September 21
In 47.5 weeks
Dot release 1

Scheduled for one week after launch, this Desktop and/or Android release targets critical quality fixes and selective feature uplifts. The deadline for uplift requests is EOD on the Friday prior to go-live. Should emergency dot releases ship earlier and resolve pending issues, the Release Management team will determine if this scheduled milestone remains necessary.

September 28
In 48.5 weeks
Milestones
181.0 branch is created

The firefox-v181.0 branch is created from the main branch. version.txt is bumped to 181.1 on main. Any further code change for the 181.0 release now requires an uplift request.

September 10
181.0 release candidate is created

The 181.0 release candidate is created based on the firefox-v181.0 branch. This build might contain additional uplifts. Additionaly, the 180.3 release is tagged as shipped.

September 10
Preliminary QA sign off on 181.0

QA gives a preliminary sign off on 181.0. 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.

September 13
Final QA sign off on 181.0 Release notes ready

QA gives its final sign off on 181.0. 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.

September 14
181.0 sent to Apple Store

We submit 181.0 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.

September 14
181.1 branch is created

The firefox-v181.1 branch is created from the main branch. version.txt is bumped to 182.0 on main. Any further code change for the 181.1 release now requires an uplift request.

September 17
181.1 release candidate is created

The 181.1 release candidate is created based on the firefox-v181.0 branch. This build might contain additional uplifts. Additionaly, the 181.0 release is tagged as shipped.

September 17
181.0 is shipped

181.0 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%.

September 20
Preliminary QA sign off on 181.1

QA gives a preliminary sign off on 181.1. 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.

September 20
Final QA sign off on 181.1 Release notes ready

QA gives its final sign off on 181.1. 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.

September 21
181.1 sent to Apple Store

We submit 181.1 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.

September 23
181.1 is shipped

181.1 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%.

September 27