Why Firefox 54?

As you probably have read by now, the regular release of Firefox 52 only allows one plugin, which is Flash. The Extended Support Release (ESR) of Firefox 52 will still run Acrobat, Java, and other old plugins. ESR was first developed to meet the needs of large organizations that wanted Firefox to change much more slowly, but anyone can run it. It will retain the features of Firefox 52 and get regular security updates through late Spring.

More information on this change and ESR: Why do Java, Silverlight, Adobe Acrobat and other plugins no longer work?

jscher2000, thank you!

Now this makes more sense somewhat. ESR branch i guess is limited by 52.x releases and doesn't go higher. No FF 54 ESR? What about the dev or the nightly builds?

And this : "Important: The Windows 64-bit version of Firefox 52 ESR only supports the Adobe Flash and Microsoft Silverlight plugins. If you also need support for Java or other installed plugins, choose the Windows (32-bit) download. "

This means that if I need FF 64 bits which I actually do, then I should choose pre 52 main branch FF?

Again thank you for your time. I saw a lot of your replies on other threads -- you are helping a lot of people.

The only currently supported release that can run the Adobe Acrobat plugin on Windows is:

Firefox 52.5.3esr 32-bit

A new Extended Support Release is created about once a year. The previous one was based on Firefox 45 and the next will be based on Firefox 60. I don't know whether plugins other than Flash will be supported in the next ESR; this might be the end of the line (Summer 2018).