Mozilla no longer hosts old ESR versions on its main site. However, the official archive is available here:
https://archive.mozilla.org/pub/firefox/releases/52.9.0esr/From there, navigate to:
win32/ or win64/ for Windowsmac/ for macOSlinux-x86_64/ or linux-i686/ for LinuxYou can find the official, unmodified installer here:
https://ftp.mozilla.org/pub/firefox/releases/52.9.0esr/ firefox version 52.9. 0 esr download
Choose your OS:
win32/ – Windows 32-bit (works on 64-bit too)win64/ – Windows 64-bitmac/ – macOSlinux-i686/ or linux-x86_64/Within each folder, download the .exe, .dmg, or .tar.bz2 file (e.g., Firefox%20Setup%2052.9.0esr.exe). Firefox Version 52
If you have already downloaded and installed the browser, here are fixes for typical problems:
| Problem | Solution |
| :--- | :--- |
| "Your browser is not secure" errors | Install an old version of uBlock Origin (legacy version 1.16.4) to block insecure scripts. |
| Can't install any extensions | Go to about:config, set xpinstall.signatures.required to false. |
| Certificate errors on HTTPS sites | Manually add root certificates (not for novices). Or use an SSL proxy in between. |
| Pages are painfully slow | Disable WebGL, hardware acceleration, and set content.notify.interval to 500000. | Mozilla FTP Archive (official) :
https://archive
If you have a machine running Windows XP or Windows Vista, mainstream browsers no longer function. Google Chrome dropped XP in 2016, and modern Firefox (version 115+ is the last for Windows 7/8, not XP). Firefox 52.9.0 ESR is likely the most secure, modern browser that can physically run on these antique OSes. It allows you to:
