Hello,
Firefox 52.9.1 ESR has actually been released here, but apparently, it has not made it into PortableApps yet:
https://download-origin.cdn.mozilla.net/pub/firefox/tinderbox-builds/moz...
https://download-origin.cdn.mozilla.net/pub/firefox/tinderbox-builds/moz...
As far as we know, this is the latest single-process-capable Firefox version released, and has many security patches that have been backported.
The latest PortableApp that has been released is 52.9.0 ESR released here:
https://portableapps.com/apps/internet/firefox-portable-legacy-52
So, we kindly request that 52.9.1 ESR be released as a PortableApp.
As a side note, if anyone knows if 52.9 ESR (AKA single-process Firefox) is continuing to be developed anywhere (even if not by Mozilla), please let us know.
Thanks!
You should always report outdated apps here: https://portableapps.com/development/outdated
For future reference, it's linked from the Development and Support sections as well as a big "Before you post" header when creating a new forum topic.
As to the specific question, we only maintain two ESR releases as per: https://portableapps.com/support/firefox_portable#esr
The release you are linking to was not officially released by Mozilla, so we don't package it. It's a tinderbox build. You can see official releases here, noting a lack of ESR 52.9.1: http://archive.mozilla.org/pub/firefox/releases/
If Mozilla does release it, we will package it.
Sometimes, the impossible can become possible, if you're awesome!