Firefox 155 End of Life
Support dates and upgrade guidance — rebuilt from live data.
End of Life
Firefox 155 reached end of life on 15 Sept 2026. It no longer receives security fixes.
20 days without security patches
Recommended action: upgrade to Firefox 157. Check your versionfirefox --version
Support timeline
Official dates from the Firefox release process.
| Milestone | Date | Status |
|---|---|---|
| Initial release | 1 Sept 2026 | 1mo ago |
| Security Support ended | 15 Sept 2026 | 1mo ago |
| Latest release | 155.0.1 · 4 Sept 2026 | final |
Where to go from 155
Recommended target: Firefox 157.
The newest actively supported branch is Firefox 157 (latest release 157.0).
Frequently asked questions
Is Firefox 155 still safe to use?
Firefox 155 reached end of life on 15 Sept 2026, 20 days ago, and is no longer covered by standard support. Running it means no guaranteed security fixes.
Can I still download Firefox 155?
Yes — the final release (155.0.1) generally remains available from vendor archives and OS package mirrors, but installing it means running software with known, unpatched vulnerabilities.
What should I upgrade Firefox 155 to?
Upgrade to Firefox 157, the newest actively supported branch.
All Firefox versions
157 supported 156 EOL 2026 155 EOL 2026 154 EOL 2026 153 supported 152 EOL 2026 151 EOL 2026 150 EOL 2026 149 EOL 2026 148 EOL 2026 147 EOL 2026 146 EOL 2026 145 EOL 2025 144 EOL 2025 143 EOL 2025 142 EOL 2025 141 EOL 2025 140 EOL 2026 139 EOL 2025 138 EOL 2025 137 EOL 2025 136 EOL 2025 135 EOL 2025 134 EOL 2025 133 EOL 2025 132 EOL 2024 131 EOL 2024 130 EOL 2024 129 EOL 2024 128 EOL 2025 127 EOL 2024 126 EOL 2024 125 EOL 2024 124 EOL 2024 123 EOL 2024 122 EOL 2024 121 EOL 2024 120 EOL 2023 119 EOL 2023 118 EOL 2023 117 EOL 2023 116 EOL 2023 115 supported 114 EOL 2023 113 EOL 2023 112 EOL 2023 111 EOL 2023 110 EOL 2023 109 EOL 2023 108 EOL 2023 107 EOL 2022 106 EOL 2022 105 EOL 2022 104 EOL 2022 103 EOL 2022 102 EOL 2023 91 EOL 2022 78 EOL 2021