| Release Date | September 15, 2026 |
|---|---|
| Release Owner | Donal Meehan |
| Corresponding ESR releases | 153.3.0 · 140.16.0 · 115.41.0? |
| Nightly cycle length | 2 weeks |
| Beta cycle length | 2 weeks |
| Milestones | |
|---|---|
Deadline to request manual QAQA 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 6 In 2 weeks |
Deadline to request accessibility engineering reviewAccessibility engineering review has been requested (using the |
August 13 In 3 weeks |
Nightly startsThe 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. |
August 13 In 3 weeks |
Build ready for QAFeatures 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 21 In 4 weeks |
QA Test Plan approval dueThe 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 21 In 4 weeks |
Strings hand-off to engineeringFinal strings are handed off to Engineering to ensure they are landed before localization begins. |
August 26 In 5 weeks |
String Freeze startsIn 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. |
August 26 In 5 weeks |
Draft beta release notesA 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. |
August 27 In 5 weeks |
Nightly QA sign-offQA signs off on the Nightly build, assessing its readiness for shipping to Beta by running a set of regression test cases and sharing a test report. |
August 27 In 5 weeks |
Merge dayThis 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 156 and the beginning of our Beta stabilization cycle. |
August 27 In 5 weeks |
Beta 1First beta of the cycle, rolled out to our beta population. Build starts at 13:00 UTC. Stabilization work via uplifts. |
August 31 In 5.5 weeks |
Beta 2First automated beta of the cycle. It is rolled out to 100% of our beta population. Build starts at 13:00 UTC. |
September 2 In 6 weeks |
SUMO content creationUser 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 2 In 6 weeks |
Beta 3Build starts at 13:00 UTC. Stabilization work via uplifts. |
September 4 In 6 weeks |
Beta 4Build starts at 13:00 UTC. Stabilization work via uplifts. |
September 7 In 6.5 weeks |
Beta 5 Security bugs uplift request deadline Last beta upliftsLast beta of the cycle and thus the end of beta uplifts. This is also the deadline for security bugs uplift requests ( |
September 9 In 7 weeks |
Release notes submission deadlineAll 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 10 In 7 weeks |
Release Candidate Go to buildWe 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. |
September 10 In 7 weeks |
Release day!Firefox 156 ships at 13:00 UTC (6 AM PT) with an initial 25% rollout. |
September 15 In 7.5 weeks |
Dot release 1Scheduled 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 22 In 8.5 weeks |
| Milestones | |
|---|---|
156.0 branch is createdThe |
September 4 |
156.0 release candidate is createdThe 156.0 release candidate is created based on the |
September 4 |
Preliminary QA sign off on 156.0QA gives a preliminary sign off on 156.0. 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 7 |
Final QA sign off on 156.0 Release notes readyQA gives its final sign off on 156.0. 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 8 |
156.0 sent to Apple StoreWe submit 156.0 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 8 |
156.1 branch is createdThe |
September 11 |
156.1 release candidate is createdThe 156.1 release candidate is created based on the |
September 11 |
156.0 is shipped156.0 is shipped on the Apple Store at 3:00 AM UTC with a phased 7 days rollout: |
September 14 |
Preliminary QA sign off on 156.1QA gives a preliminary sign off on 156.1. 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 14 |
Final QA sign off on 156.1 Release notes readyQA gives its final sign off on 156.1. 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 15 |
156.1 sent to Apple StoreWe submit 156.1 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 17 |
156.1 is shipped156.1 is shipped on the Apple Store at 3:00 AM UTC with a phased 7 days rollout: |
September 21 |