Your hardware is no longer supported

If your computer has a processor older than Pentium 4, Firefox version 49 and above is no longer supported.

If Firefox is already installed on your computer, you can continue using it but you will not receive updates beyond version 48. If you download Firefox version 49 or above and try to install it, you will see the message, Firefox cannot be installed. This version of Firefox requires a processor with SSE2 support.

Like many programs, newer versions of Firefox require a processor that supports Streaming SIMD Extensions 2 (SSE2) for better security and performance. We recommend a computer with a Pentium 4 or newer processor that supports SSE2 to use the latest version of Firefox, which has more features, stability and security.

Firefox Extended Support Release (ESR) will continue to work with older processors but will not receive updates beyond ESR version 45. Firefox ESR version 52, scheduled for release in March 2017, will no longer be supported.

If your computer has a processor older than Pentium 4, Firefox version 53 and above is no longer supported.

If Firefox is already installed on your computer, you can continue using it but you will not receive updates beyond version 53. If you download Firefox version 53 or above and try to run it, you will see the message in stderr, This browser version requires a processor with the SSE2 instruction set extension. You may be able to obtain a version that does not require SSE2 from your Linux distribution.

Like many programs, newer versions of Firefox require a processor that supports Streaming SIMD Extensions 2 (SSE2) for better performance. We recommend a computer with a Pentium 4 or newer processor that supports SSE2 to use the latest version of Firefox, which has more features, stability and security.

Firefox Extended Support Release (ESR) will continue to work with older processors but will not receive updates beyond ESR version 52. Firefox ESR version 59, scheduled for release in March 2018, will no longer be supported.

The processor requirements of Firefox as distributed by Linux distributions may differ from the processor requirements of Firefox as distributed by Mozilla, so you may be able to obtain an up-to-date version of Firefox that does not require SSE2 from your Linux distribution.