This is a staging environment for whattrainisitnow.com

Upcoming Firefox release milestones

August 2026
SMTWTFS
1
2
3
154 b7 GTB
SUMO content localization starts
4
5
154 b8 GTB
154 QA sign off
6
7
154 b9 GTB
8
9
10
154 go to Build
11
RC
12
13
155 soft Code Freeze starts at 08:00 UTC
14
155 string freeze starts
155 regression testing completed
156 QA request deadline
156 a11y engineering request deadline for Nightly
15
16
17
Merge day
155 b1 GTB
Nightly 156 starts
18
154 Release
155 b1
19
155 b2 GTB
20
21
155 b3 GTB
SUMO deadline
22
23
24
155 b4 GTB
25
Potential Android 154.0.x
26
155 b5 GTB
27
28
155 b6 GTB
156 build ready for QA
Final deadline for QA’s Feature Test Plan approval
29
30
31
155 b7 GTB
SUMO content localization starts

September 2026
SMTWTFS
1
Planned 154.0.x
2
155 b8 GTB
155 QA sign off
3
4
155 b9 GTB
5
6
7
155 go to Build
8
RC
9
10
156 soft Code Freeze starts at 08:00 UTC
11
156 string freeze starts
156 regression testing completed
157 QA request deadline
157 a11y engineering request deadline for Nightly
12
13
14
Merge day
156 b1 GTB
Nightly 157 starts
15
155 Release
156 b1
16
156 b2 GTB
17
18
156 b3 GTB
SUMO deadline
19
20
21
156 b4 GTB
22
Potential Android 155.0.x
23
156 b5 GTB
24
25
156 b6 GTB
157 build ready for QA
Final deadline for QA’s Feature Test Plan approval
26
27
28
156 b7 GTB
SUMO content localization starts
29
Planned 155.0.x
30
156 b8 GTB
156 QA sign off

October 2026
SMTWTFS
1
2
156 b9 GTB
3
4
5
156 go to Build
6
RC
7
8
157 soft Code Freeze starts at 08:00 UTC
9
157 string freeze starts
157 regression testing completed
158 QA request deadline
158 a11y engineering request deadline for Nightly
10
11
12
Merge day
157 b1 GTB
Nightly 158 starts
13
156 Release
157 b1
14
157 b2 GTB
15
16
157 b3 GTB
SUMO deadline
17
18
19
157 b4 GTB
20
Potential Android 156.0.x
21
157 b5 GTB
22
23
157 b6 GTB
158 build ready for QA
Final deadline for QA’s Feature Test Plan approval
24
25
26
157 b7 GTB
SUMO content localization starts
27
Planned 156.0.x
28
157 b8 GTB
157 QA sign off
29
30
157 b9 GTB
31

November 2026
SMTWTFS
1
2
157 go to Build
3
RC
4
5
158 soft Code Freeze starts at 08:00 UTC
6
158 string freeze starts
158 regression testing completed
159 QA request deadline
159 a11y engineering request deadline for Nightly
7
8
9
Merge day
158 b1 GTB
Nightly 159 starts
10
157 Release
158 b1
11
158 b2 GTB
12
13
158 b3 GTB
SUMO deadline
14
15
16
158 b4 GTB
17
Potential Android 157.0.x
18
158 b5 GTB
19
20
158 b6 GTB
159 build ready for QA
Final deadline for QA’s Feature Test Plan approval
21
22
23
158 b7 GTB
SUMO content localization starts
24
Planned 157.0.x
25
158 b8 GTB
158 QA sign off
26
27
158 b9 GTB
28
29
30
158 go to Build

December 2026
SMTWTFS
1
RC
2
3
159 soft Code Freeze starts at 08:00 UTC
4
159 string freeze starts
159 regression testing completed
5
6
7
Merge day
159 b1 GTB
8
158 Release
159 b1
9
159 b2 GTB
10
11
159 b3 GTB
SUMO deadline
12
13
14
159 b4 GTB
15
Potential Android 158.0.x
16
159 b5 GTB
17
18
159 b6 GTB
19
20
21
159 b7 GTB
SUMO content localization starts
22
Planned 158.0.x
23
159 b8 GTB
159 QA sign off
24
25
26
27
28
29
30
31

January 2027
SMTWTFS
1
2
3
4
159 b9 GTB
5
6
159 b10 GTB
7
8
159 b11 GTB
9
10
11
159 go to Build
12
RC
13
14
15
16
17
18
19
159 Release
20
21
22
23
24
25
26
Potential Android 159.0.x
27
28
29
30
31