Milestones and key data for Firefox 156

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
Bugs fixed in nightly	1556
Uplifts in beta	90 (1 backout)
Uplifts in RC	0 (0 backouts)
Uplifts in dot releases	0 (0 backouts)
Total number of uplifts	90
Betas	5
Release Candidates	1
Dot releases	0
Release notes	General · Developer · Enterprise

Key Milestones
Nightly start	August 18
Beta start	August 31
156.0 ^{42% adoption - 100% rollout}	September 15
Planned 156.0.x ^{Desktop and Android} The deadline for uplift requests is EOD on the Friday prior to go-live	September 22

Milestones
156.0 branch is created The `firefox-v156.0` branch is created from the `main` branch. `version.txt` is bumped to 156.1 on `main`. Any further code change for the 156.0 release now requires an uplift request.	September 4
156.0 release candidate is created The 156.0 release candidate is created based on the `firefox-v156.0` branch. This build might contain additional uplifts. Additionaly, the 155.3 release is tagged as shipped.	September 4
Preliminary QA sign off on 156.0 QA 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 ready QA 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 Store We 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 created The `firefox-v156.1` branch is created from the `main` branch. `version.txt` is bumped to 157.0 on `main`. Any further code change for the 156.1 release now requires an uplift request.	September 11
156.1 release candidate is created The 156.1 release candidate is created based on the `firefox-v156.0` branch. This build might contain additional uplifts. Additionaly, the 156.0 release is tagged as shipped.	September 11
156.0 is shipped 156.0 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 14
Preliminary QA sign off on 156.1 QA 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 ready QA 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 Store We 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 shipped 156.1 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 21