No. Going back : unfortunately 56.0.2 is no longer safe to use for every day use, but 52.5.0 ESR is! It will continue to get security updates until May 2018, and you can download and install it from this page: https://www.mozilla.org/en-US/firefox/organizations/all/ Note : Legacy Extensions will be deleted or removed in any version update after May 2018.

You should make a backup of your Profile before going back and just because: https://support.mozilla.org/en-US/kb/back-and-restore-

Please let us know if this solved your issue or if need further assistance.

Pkshadow,

Thank you.

Do I simply install the previous version without uninstalling the current? Also, will it (should it) find all of my previous configuration, extensions, and data?

BTW, it appears that the backup link that you provided is broken.

Thanks : https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

This the best way to uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files and C:\Program Files(x86) Then restart system. Then run Windows Disk Cleanup. Then run it again and click the button that says Cleanup System Files. Note: your Firefox Profile is saved.

Please let us know if this solved your issue or if need further assistance.

Pkshadow said

Thanks : https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles This the best way to uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files and C:\Program Files(x86) Then restart system. Then run Windows Disk Cleanup. Then run it again and click the button that says Cleanup System Files. Note: your Firefox Profile is saved. Please let us know if this solved your issue or if need further assistance.

I actually installed the older version ( 56.0.2 (64-bit) ), and it (appears to have) brought everything back the way it was. Since, I didn't do it the way you've stated above, should I take any further action to delete any unneeded files, or did the downgrade take care of it?

Thanks. I will make this as solved.

I plan to figure out what the best way is to keep all of my current tabs and such, when upgrading to Quantum. Hopefully, there's a way to migrate nearly everything.

Thanks.

You did well to get everything back. Leave it at that since not broken. If went back to last version it is a Security risk and is not supported and will not get any updates other than forced update to ver 57.

If you haven't already, please select the answer that solves the problem. This will help other users with similar problems find the solution more easily. Thank you for contacting Mozilla Support.

Reality, which older version did you install, and from what source?

Could you provide the exact steps you went through? It would be very much appreciated. Thanks.

Varjak said

Reality, which older version did you install, and from what source? Could you provide the exact steps you went through? It would be very much appreciated. Thanks.

I downloaded and installed version 56.0.2 (64-bit) directly from the Firefox site. I didn't do anything else other than click my previous Firefox icon on the status bar and it brought up my previous configuration and everything just the way I had it prior to Quantum being installed.

Do you have the link? I could only find 56.0.2 on FileHippo. When I go to the 56.0.2 page, the download link references 'new,' so I'm afraid that it will download the new one (Quantum) all over again.

https://www.mozilla.org/en-US/firefox/56.0.2/releasenotes/

Did you uninstall Quantum first or just install 56.0.2 over it?

All your extensions and add-ons automatically came back? I'm primarily concerned with Session Manager and History Sub-menus. Do you use those?

I'm trying to make sure I can get my last session back.

If you could provide the steps and links (i.e. I went to site x and downloaded Firefox and followed the install wizard) etc.

I just wanted to thank Reality publicly. I downloaded 56.0.2 from the link Reality provided:

https://download-installer.cdn.mozilla.net/pub/firefox/releases/56.0.2/win64/en-US/Firefox%20Setup%2056.0.2.exe

I clicked the file and followed the installation wizard and it restored everything (other than Video Downloadhelper, where I needed to reinstall the older version as the newest one doesn't work with 56.0.2). Everything else was there including Session Manager and History Submenus.

One odd note, the taskbar icon and desktop icon seem to be the updated version, but I don't carer.