Last week the FileHippo update checker kept insisting that Firefox 38.0.6 was the latest version. I was – and still am – unable to find any official release notes for that version, but according to one source, 38.0.6 is a special version for specific hardware. In any case, Firefox never updated itself to 38.0.6.

Yesterday I discovered that Firefox 39.0 had been released, apparently on June 30th. According to its release notes, this version includes a variety of fixes and improvements, especially for Macs. HTML5 support is improved, as is networking. Several security vulnerabilities were also addressed.

Meanwhile, in reviewing the official list of Firefox releases, I found notes for version 38.1.0, which was apparently released on July 2nd. It looks like Mozilla staff posted this version in the wrong place, because the 38.1.0 release is for the ‘ESR channel’. Readers of this site are likely more interested (as am I), in the ‘release channel’. According to the Firefox ESR FAQ:

Mozilla Firefox ESR is meant for organizations that manage their client desktops, including schools, businesses and other instituitions that want to offer Firefox. Users who want to get the latest features, performance enhancements and technologies in their browsing experience should download Firefox for personal use [ed: the release channel], as these improvements will only be available to ESR users several development cycles after being made available in Firefox for desktop.

In other words, pay no attention to the 38.1.0 ESR release if you want all the latest improvements. The ESR releases tend to lag behind in features, while typically being more stable.