This is a staging environment for whattrainisitnow.com

«  Firefox 157  »

3% adoption rate
Release DateSeptember 29, 2026
Release OwnerPascal Chevrel
Corresponding ESR releases 153.4.0 · 140.17.0 · 115.42.0?
Nightly cycle length2 weeks
Beta cycle length2 weeks
Bugs fixed in nightly 1370
Uplifts in beta157 (0 backouts)
Uplifts in RC4 (0 backouts)
Uplifts in dot releases0 (0 backouts)
Total number of uplifts161
Betas5
Release Candidates1
Dot releases0
Release notes General · Developer · Enterprise
Key Milestones
Nightly start September 1
Beta start September 14
157.0 3% adoption - 25% rollout September 29
Planned 157.0.x Desktop and Android
The deadline for uplift requests is EOD on the Friday prior to go-live 		October 6
Milestones
157.0 branch is created

The firefox-v157.0 branch is created from the main branch. version.txt is bumped to 157.1 on main. Any further code change for the 157.0 release now requires an uplift request.

 September 18
157.0 release candidate is created

The 157.0 release candidate is created based on the firefox-v157.0 branch. This build might contain additional uplifts. Additionaly, the 156.3 release is tagged as shipped.

 September 18
Preliminary QA sign off on 157.0

QA gives a preliminary sign off on 157.0. 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 21
Final QA sign off on 157.0 Release notes ready

QA gives its final sign off on 157.0. 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 22
157.0 sent to Apple Store

We submit 157.0 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 22
157.1 branch is created

The firefox-v157.1 branch is created from the main branch. version.txt is bumped to 158.0 on main. Any further code change for the 157.1 release now requires an uplift request.

 September 25
157.1 release candidate is created

The 157.1 release candidate is created based on the firefox-v157.0 branch. This build might contain additional uplifts. Additionaly, the 157.0 release is tagged as shipped.

 September 25
157.0 is shipped

157.0 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 28
Preliminary QA sign off on 157.1

QA gives a preliminary sign off on 157.1. 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 28
Final QA sign off on 157.1 Release notes ready

QA gives its final sign off on 157.1. 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 29
157.1 sent to Apple Store

We submit 157.1 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 1
157.1 is shipped

157.1 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 5