The Complete Legacy Firefox Guide: Archiving and Installing Versions 12 to 51 and 52 ESR
If the browser is only needed to configure local hardware (such as an old network switch or router), block the browser or the host VM from accessing the wider internet via your firewall. Download Firefox 12-51 52 Esr
Select your operating system (e.g., win32 , win64 , mac , or linux-x86_64 ). The Complete Legacy Firefox Guide: Archiving and Installing
Quick checklist
Uncheck "Use the selected profile without asking at startup" to easily toggle between different versions. 3. Resolving Modern TLS / SSL Handshake Errors Download Firefox 12-51 52 Esr
This is the absolute final update for the 52 series, released in June 2018 to provide the last security fixes for older operating systems. 2. Where to Download Safely