Where are you downloading it from? From here - https://ftp.mozilla.org/pub/firefox/releases/50.0/mac/en-US/ ?

Is there a reason you need v50?

Note: Some versions of Quantum change how the data files are set up, so they are not backward compatible.

Hi Brisdaz, thank you for provided the link, are you also able to provide me with Mozilla Firefox version 52.9.0 ESR for MAC?

Hi FredMcD, I need the older version, which is compatible with my employer's system platform.

You can install a portable (ESR) Firefox version to access websites that do not work with the current Firefox release.

The portable version comes with its own profile folder and doesn't interfere with currently installed Firefox versions.

• https://portableapps.com/apps/internet/firefox_portable
• https://portableapps.com/apps/internet/firefox-portable-esr
• https://sourceforge.net/projects/portableapps/files/Mozilla%20Firefox%2C%20Portable%20Ed./