Firefox ESR 91: new ESR version will be released tomorrow

Martin Brinkmann
Aug 9, 2021

Mozilla plans to release new versions of its Firefox web browser on Tuesday 10, 2021. The organization does so every 4-weeks on average, but tomorrow's release is special, as it is the base for a new ESR, Extended Support Release, version of the web browser.

Firefox ESR versions are maintained for a longer period compared to stable releases. One core difference is that they are released with a specific feature set that is not changed during the lifetime. Security updates and bug fixes are released, but features are not added usually until the next ESR version is released.

The last Firefox ESR version, Firefox 78 ESR, was released in June 2020, and it replaced Firefox 68 ESR in September 2020.

Two Firefox ESR branches are released side-by-side for a period of two or three releases usually, before the older one is not updated anymore; this gives organizations and home users enough testing and migration time.

Firefox 91 ESR won't replace Firefox 78 ESR right away. The latter will see two additional releases, Firefox 78.14 ESR and Firefox 78.15 ESR before it will be discontinued; this will happen in October 2021.

firefox 91 esr

Firefox 91 ESR marks the beginning of a new base for extended support releases. The version will be supported for about a year.

Organizations and home users who are running the current ESR version may update their installations to the new version. The upgrade is a major one, considering that Firefox 91 includes all the functionality that Mozilla introduced since the release of Firefox 78 ESR.

Major changes include the new interface design that Mozilla rolled out recently, improved privacy protections, removed Adobe Flash support, support for new operating system versions, e.g. Mac OS Big Sur, and a lot more.

Here is a short list of changes that will be introduced in Firefox 91 ESR:

Firefox ESR is also the base of the Tor Browser. The developers of the Tor browser will update the browser to the new ESR version as well, eventually.

Firefox ESR users may want to test the new version before they upgrade existing installations and profiles. You could download and run the portable version of Firefox ESR from Portable Apps for testing; it does not interfere with the active installation, as it is portable, and you could import the Firefox profile from the installed version to the portable version to test it.  Firefox ESR versions are not upgraded automatically to a new base version, this begins with the second release after the release of the new base version.

Closing Words

The new Firefox 91 base for ESR releases introduces significant changes to various features of the browser. Some features are removed, e.g. Flash support is gone for good and the interface redesign has removed some options, but there are also new features, such as improved privacy protections. Organizations who rely on these features lose another option, and need to look elsewhere, e.g. Pale Moon, for support.

Now You: Do you use the ESR version of Firefox?

Firefox ESR 91: new ESR version will be released tomorrow
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Firefox ESR 91: new ESR version will be released tomorrow
A new Firefox ESR Extended Support Release version, Firefox 91 ESR, will be released this month. Find out what is new and changed in the release.
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  1. Mr_Yesterday said on February 9, 2022 at 8:26 pm

    Oh lord, proton is awful and wastes so much page space on a traditional PC. I had the need to flash back to a mirror backup from early 2020 and I’m looking at Firefox 75.0. This was so much better in terms of visual feel, space saving, thin clean lines, easy functionality, and comprehensive yet still detailed options pages (with icons!). It was not reliant on hamburger menu only, etc, etc. So I looked at ESR and apparently I can’t get the last version and even ESR is new proton. Bummer. I’m really tired of dealing with firefoxes never ending graphics changes and I do not agree that the entire appeal and visual functionality needs to be changed for everyone. As many others have suggested, Firefox should allow a traditional firefox experience and label that as a PC Traditional install or something. They changed the entire program for mobile devices, to the detriment of efficient PC users. Going to run a regedit hack or some sort of block to stop firefox from updating and just freeze it at 75.0 because that was good enough and it’s awesome. Tired of needing to dip into about config, do stupid things like r click to view image needing a special add on, wasted space with annoyingly large columns and space between, rounded, hamburger, css files to get bookmarks back to the nice way it used to be where I could view as many bookmarked sites that would fit into those tiny small lines, all of it. I’m looking at my top space reserved for browser items on 75.0 vs current 96.03 I have, and the total bar set width is 30% or more larger in the ‘new version’. Dude, firefox needs a classic install for PC users and you know what, about config is enough and we don’t want any more graphic or interface changes unless that’s ran through as optional inclusions. Please can the tech guys take a very long vacation and offer all ffx users an integrated ESR option where all we get is security updates. It could be as simple as accept more than security fixes y/n option. From all the edits to win10 to firefox, getting tiresome and no fun. Coming back from getting hacked takes less time than setting up the dang software these days, geesh.

  2. Sefer_HaMalbush said on August 10, 2021 at 11:16 am

    Waiting for LibreWolf to release.

  3. Proudly Brave said on August 10, 2021 at 8:27 am

    This browser is excellent because it is not racist or homophobic. Whether that results in a good browsing experience is not debatable, homophobic, islamophobic and racist.
    I only wish it would be offered without Google search, but I guess that’s too much to ask for.

    1. ShintoPlasm said on August 10, 2021 at 10:39 am

      How can a browser be racist or homophobic? Do explain.

    2. CHUDs GTFO said on August 10, 2021 at 10:36 am

      Are you okay? It must really suck to feel like cultural progress comes at your personal expense. Kind of sad, but no one feels bad for you.

  4. Dave said on August 10, 2021 at 5:40 am

    When you use the phrase “privacy protection” in the same sentence as “browser” what it really means is that that browser is protecting it’s own monetary interests by trying to prevent your data from being harvested by anyone but them.

  5. yanta said on August 10, 2021 at 3:45 am

    I would argue that esr is the “stable” version, where as the ever changing retail channel that gets a bug fix after almost every new release is not so stable.

    Now begins the months long testing of 91esr to figure out how to add back everything they’ve taken out, and all the settings that have been deprecated to try to turn it back into a useful browser.

  6. Yuliya said on August 9, 2021 at 11:22 pm

    New UI and other unnwanted features nobody asked for, more telemetry, forced updates, less features; and yet this VSync bug is still present:
    An issue so old, it’s laughable. Funnily, this means Firefox is still not Vista or newer compliant. They’ll fully run it to the ground and this bug will still not be fixed by then.

  7. ULBoom said on August 9, 2021 at 10:16 pm

    I’ll update when I have to. I played with fast release 90 a month or so ago, in beta or something and it behaved fine. Prefs from ESR 78 seemed to transfer OK. Easy to remove, change, disable all the new improved stuff such as the Googlus Giganticus interface. Flash is already gone from our systems and the security stuff done outside the browser.

  8. Anonymous said on August 9, 2021 at 9:29 pm

    I hope that “browser.proton.enabled” will still be configurable.

    1. Anonymous said on August 12, 2021 at 10:41 am

      It isn’t.

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