This is a staging environment for whattrainisitnow.com

Upcoming Firefox release milestones

February 2026
SMTWTFS
1
2
148 b10 GTB
3
4
Planned 147.0.x
148 b11 GTB
148 QA sign off
5
6
148 b12 GTB
149 build ready for QA
Final deadline for QA’s Feature Test Plan approval
7
8
9
148 b13 GTB
10
11
148 b14 GTB
12
13
148 b15 GTB
14
15
16
148 go to Build
17
RC
18
149 beta release notes ready
19
20
149 string freeze starts
149 regression testing completed
150 QA request deadline
150 a11y engineering request deadline for Nightly
21
22
23
Merge day
Nightly 150 starts
24
148 Release
25
149 b1 GTB
26
27
149 b2 GTB
SUMO deadline
28

March 2026
SMTWTFS
1
2
149 b3 GTB
3
Potential Android 148.0.x
4
149 b4 GTB
5
6
149 b5 GTB
150 build ready for QA
Final deadline for QA’s Feature Test Plan approval
7
8
9
149 b6 GTB
SUMO content localization starts
10
Planned 148.0.x
11
149 b7 GTB
149 QA sign off
12
13
149 b8 GTB
14
15
16
149 b9 GTB
17
149 release notes deadline
18
149 b10 GTB
149 go to Build
RC
150 beta release notes ready
19
20
150 string freeze starts
150 regression testing completed
151 QA request deadline
151 a11y engineering request deadline for Nightly
21
22
23
Merge day
Nightly 151 starts
24
149 Release
25
150 b1 GTB
26
27
150 b2 GTB
SUMO deadline
28
29
30
150 b3 GTB
31
Potential Android 149.0.x

April 2026
SMTWTFS
1
150 b4 GTB
2
3
150 b5 GTB
151 build ready for QA
Final deadline for QA’s Feature Test Plan approval
4
5
6
150 b6 GTB
SUMO content localization starts
7
Planned 149.0.x
8
150 b7 GTB
150 QA sign off
9
10
150 b8 GTB
11
12
13
150 b9 GTB
14
150 release notes deadline
15
150 b10 GTB
150 go to Build
RC
151 beta release notes ready
16
17
151 string freeze starts
151 regression testing completed
152 QA request deadline
152 a11y engineering request deadline for Nightly
18
19
20
Merge day
Nightly 152 starts
21
150 Release
22
151 b1 GTB
23
24
151 b2 GTB
SUMO deadline
25
26
27
151 b3 GTB
28
Potential Android 150.0.x
29
151 b4 GTB
30

May 2026
SMTWTFS
1
151 b5 GTB
152 build ready for QA
Final deadline for QA’s Feature Test Plan approval
2
3
4
151 b6 GTB
SUMO content localization starts
5
Planned 150.0.x
6
151 b7 GTB
151 QA sign off
7
8
151 b8 GTB
9
10
11
151 b9 GTB
12
151 release notes deadline
13
151 b10 GTB
151 go to Build
RC
152 beta release notes ready
14
15
152 string freeze starts
152 regression testing completed
153 QA request deadline
153 a11y engineering request deadline for Nightly
16
17
18
Merge day
Nightly 153 starts
19
151 Release
20
152 b1 GTB
21
22
152 b2 GTB
SUMO deadline
23
24
25
152 b3 GTB
26
Potential Android 151.0.x
27
152 b4 GTB
28
29
152 b5 GTB
153 build ready for QA
Final deadline for QA’s Feature Test Plan approval
30
31

June 2026
SMTWTFS
1
152 b6 GTB
SUMO content localization starts
2
Planned 151.0.x
3
152 b7 GTB
152 QA sign off
4
5
152 b8 GTB
6
7
8
152 b9 GTB
9
152 release notes deadline
10
152 b10 GTB
152 go to Build
RC
153 beta release notes ready
11
12
153 string freeze starts
153 regression testing completed
154 QA request deadline
154 a11y engineering request deadline for Nightly
13
14
15
Merge day
Nightly 154 starts
16
152 Release
17
153 b1 GTB
18
19
153 b2 GTB
SUMO deadline
20
21
22
153 b3 GTB
23
Potential Android 152.0.x
24
153 b4 GTB
25
26
153 b5 GTB
27
28
29
153 b6 GTB
SUMO content localization starts
30
Planned 152.0.x

July 2026
SMTWTFS
1
153 b7 GTB
153 QA sign off
2
3
153 b8 GTB
154 build ready for QA
Final deadline for QA’s Feature Test Plan approval
4
5
6
153 b9 GTB
7
8
153 b10 GTB
9
10
153 b11 GTB
11
12
13
153 b12 GTB
14
153 release notes deadline
15
153 b13 GTB
153 go to Build
RC
154 beta release notes ready
16
17
154 string freeze starts
154 regression testing completed
155 QA request deadline
155 a11y engineering request deadline for Nightly
18
19
20
Merge day
Nightly 155 starts
21
153 Release
22
154 b1 GTB
23
24
154 b2 GTB
SUMO deadline
25
26
27
154 b3 GTB
28
Potential Android 153.0.x
29
154 b4 GTB
30
31
154 b5 GTB
155 build ready for QA
Final deadline for QA’s Feature Test Plan approval

August 2026
SMTWTFS
1
2
3
154 b6 GTB
SUMO content localization starts
4
Planned 153.0.x
5
154 b7 GTB
154 QA sign off
6
7
154 b8 GTB
8
9
10
154 b9 GTB
11
154 release notes deadline
12
154 b10 GTB
154 go to Build
RC
155 beta release notes ready
13
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
Nightly 156 starts
18
154 Release
19
155 b1 GTB
20
21
155 b2 GTB
SUMO deadline
22
23
24
155 b3 GTB
25
Potential Android 154.0.x
26
155 b4 GTB
27
28
155 b5 GTB
156 build ready for QA
Final deadline for QA’s Feature Test Plan approval
29
30
31
155 b6 GTB
SUMO content localization starts

September 2026
SMTWTFS
1
Planned 154.0.x
2
155 b7 GTB
155 QA sign off
3
4
155 b8 GTB
5
6
7
155 b9 GTB
8
155 release notes deadline
9
155 b10 GTB
155 go to Build
RC
156 beta release notes ready
10
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
Nightly 157 starts
15
155 Release
16
156 b1 GTB
17
18
156 b2 GTB
SUMO deadline
19
20
21
156 b3 GTB
22
Potential Android 155.0.x
23
156 b4 GTB
24
25
156 b5 GTB
157 build ready for QA
Final deadline for QA’s Feature Test Plan approval
26
27
28
156 b6 GTB
SUMO content localization starts
29
Planned 155.0.x
30
156 b7 GTB
156 QA sign off

October 2026
SMTWTFS
1
2
156 b8 GTB
3
4
5
156 b9 GTB
6
156 release notes deadline
7
156 b10 GTB
156 go to Build
RC
157 beta release notes ready
8
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
Nightly 158 starts
13
156 Release
14
157 b1 GTB
15
16
157 b2 GTB
SUMO deadline
17
18
19
157 b3 GTB
20
Potential Android 156.0.x
21
157 b4 GTB
22
23
157 b5 GTB
158 build ready for QA
Final deadline for QA’s Feature Test Plan approval
24
25
26
157 b6 GTB
SUMO content localization starts
27
Planned 156.0.x
28
157 b7 GTB
157 QA sign off
29
30
157 b8 GTB
31

November 2026
SMTWTFS
1
2
157 b9 GTB
3
157 release notes deadline
4
157 b10 GTB
157 go to Build
RC
158 beta release notes ready
5
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
Nightly 159 starts
10
157 Release
11
158 b1 GTB
12
13
158 b2 GTB
SUMO deadline
14
15
16
158 b3 GTB
17
Potential Android 157.0.x
18
158 b4 GTB
19
20
158 b5 GTB
159 build ready for QA
Final deadline for QA’s Feature Test Plan approval
21
22
23
158 b6 GTB
SUMO content localization starts
24
Planned 157.0.x
25
158 b7 GTB
158 QA sign off
26
27
158 b8 GTB
28
29
30
158 b9 GTB

December 2026
SMTWTFS
1
158 release notes deadline
2
158 b10 GTB
158 go to Build
RC
159 beta release notes ready
3
4
159 string freeze starts
159 regression testing completed
5
6
7
Merge day
8
158 Release
9
159 b1 GTB
10
11
159 b2 GTB
SUMO deadline
12
13
14
159 b3 GTB
15
Potential Android 158.0.x
16
159 b4 GTB
17
18
159 b5 GTB
19
20
21
159 b6 GTB
SUMO content localization starts
22
Planned 158.0.x
23
159 b7 GTB
24
25
26
27
28
29
30
31

January 2027
SMTWTFS
1
2
3
4
159 b8 GTB
5
6
159 b9 GTB
159 QA sign off
7
8
159 b10 GTB
9
10
11
159 b11 GTB
12
159 release notes deadline
13
159 b12 GTB
159 go to Build
RC
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