Not sure what you mean by updating from Firefox 115.16.1esr to ESR ?.

Also your settings are in the Profile folder and not in the Firefox folder or such. https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

Firefox 115.16.1 is a ESR version as it is the old ESR channel branch still being supported with updates at least until Fx 115.21.0esr in March 2025. The old Fx 115 ESR is being updated for Windows 7, 8, 8.1 and macOS 10.12, 10.13, 10.14 users in mind. The current ESR channel is at Fx 128.3.1 ESR.

However Firefox versions since 116.0 or later including the Firefox 131.0.2 Release and Firefox 128.3.1 ESR requires macOS 10.15 (ten.fifteen) at minimum to run so you will not be able to run Firefox 128 ESR on the old macOS 1013.6

https://support.mozilla.org/en-US/kb/firefox-users-macos-1012-1013-1014-moving-to-extended-support

See also:

• https://support.mozilla.org/en-US/kb/recover-user-data-missing-after-firefox-update

Thanks very much for this. I think I have been using Firefox 115.15.1 for quite some time, apparently without realizing it is an ESR version. When trying to access a particular web page, I received a message saying that I should upgrade to the current ESR version to continue to use that site. As a consequence, I downloaded the newest version, which seems to be 115.16.1esr, but when I opened this version of Firefox, all of my bookmarks, extensions and other setting seem to have been lost (including the option to require logging in with my password when I open the new version of Firefox). I'm hoping there is a way to simply import everything from the 115.15.1 version. I have both versions open on my computer, and they both seem to work fine, but it sounds like I should now use only the 115.16.1esr version. . .

Thanks for any advice you can provide.

I tried https://support.mozilla.org/en-US/kb/recover-user-data-missing-after-firefox-update, but there is no option to "launch profile in new browser", so, a dead end. Thanks though . . .

Do you have one profile or more?

I seem, now, to have two. One that operates in the older version 11.15.1 and one in the new version 11.16.1esr. I presume the new one is empty. I'd like to move the one that operates into the older version into the newer version . . . Thanks!

Can you click "Set as default profile"?