Milestones and key data for Firefox 158

Release Date	October 13, 2026
Release Owner	Dianna Smith
Corresponding ESR releases	153.5.0 · 115.43.0^?
Nightly cycle length	2 weeks
Beta cycle length	2 weeks
Bugs fixed in nightly	1759
Uplifts in beta	76 (0 backouts)
Uplifts in RC	0 (0 backouts)
Uplifts in dot releases	0 (0 backouts)
Total number of uplifts	76
Betas	5
Release Candidates	2
Dot releases	0
Release notes	General · Developer · Enterprise

Key Milestones
Nightly start	September 15
Beta start	September 28
158.0 ^{66% adoption - 100% rollout}	October 13
Planned 158.0.x ^{Desktop and Android} The deadline for uplift requests is EOD on the Friday prior to go-live	October 20

Milestones
158.0 branch is created The `firefox-v158.0` branch is created from the `main` branch. `version.txt` is bumped to 158.1 on `main`. Any further code change for the 158.0 release now requires an uplift request.	October 2
158.0 release candidate is created The 158.0 release candidate is created based on the `firefox-v158.0` branch. This build might contain additional uplifts. Additionaly, the 157.3 release is tagged as shipped.	October 2
Preliminary QA sign off on 158.0 QA gives a preliminary sign off on 158.0. 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.	October 5
Final QA sign off on 158.0 Release notes ready QA gives its final sign off on 158.0. 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.	October 6
158.0 sent to Apple Store We submit 158.0 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.	October 6
158.1 branch is created The `firefox-v158.1` branch is created from the `main` branch. `version.txt` is bumped to 159.0 on `main`. Any further code change for the 158.1 release now requires an uplift request.	October 9
158.1 release candidate is created The 158.1 release candidate is created based on the `firefox-v158.0` branch. This build might contain additional uplifts. Additionaly, the 158.0 release is tagged as shipped.	October 9
158.0 is shipped 158.0 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%.	October 12
Preliminary QA sign off on 158.1 QA gives a preliminary sign off on 158.1. 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.	October 12
Final QA sign off on 158.1 Release notes ready QA gives its final sign off on 158.1. 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.	October 13
158.1 sent to Apple Store We submit 158.1 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.	October 15
158.1 is shipped 158.1 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%.	October 19