Sorry to hear about this. Did Firefox mention creating a new profile during installation of the update?

Either way, try the steps in the first section of the following article: Recover lost or missing Bookmarks.

Or did Firefox mention a Refresh, Reset or Tune-up? In that case, check for an "Old Firefox Data" folder on your desktop. If you have one, check the freshness of the data inside. If that is your most recent data, you could try a transplant to "undo" the Refresh. See: https://support.mozilla.org/en-US/questions/1474421#answer-1687884

Ref. Refresh Firefox - reset add-ons and settings

Thanks so much for reaching out.

But no. I checked. Firefox is using the same profile as earlier. But the Extensions folder in the Profile is empty now. I don't know of any other similar damage caused to the other folders.

No. Firefox didn't mention any such thing, as a Refresh/Reset/Tune-up. I just restarted the PC. And later when I launched Firefox it started up like this. It didn't even let me know that it had auto-updated.

I also checked the "Old Firefox Data". It is not a recent one, but a much older one.

I am little scared of using the Refresh Firefox feature. Because the word "Refresh" to me signified that everything would be as it is, except for redundant files, cookies, temp files, remnants from previous browsing, etc, would be cleaned. Just like these other system cleaners like Piriform works. Hardly did I know that the way Firefox defines the word 'Refresh' is to wipe out everything similar to a total uninstall, and then a fresh install, and that it would wipe out all the tabs, even pinned tabs, and history, everything, and then come to me and say, 'Hey here, see I have refreshed Firefox, there you go'. I had to spend quite some time to get back to where I was, which I determined that I would never again, ever trust Firefox to refresh or tune up my browser again.

Sorry to dump all this on you. But really, thanks so much for helping out.

Warm Regards Shrikant

To be clear, I did not recommend a Refresh.

Have you restarted Windows since this debacle occurred, in case there are any problems with locked files or folders?

I cannot think of a reason for the Extensions folder to be emptied during an update. I haven't heard of that happening in past updates, although I can't read everything.

You could compare the contents of

%APPDATA%\Mozilla\Firefox\Profiles

with the about:profiles page to see whether there are any folders on disk that Firefox does not know about.

Yes absolutely. You didn't recommend a Refresh. It's just that I happened to read that referred link on Refreshing Firefox, and re-lived the trauma of doing that earlier.

Answering the rest. Yes, actually the Update silently happened after a restart.

I do agree. Deleting data, and folders set up by an user arbitrarily is very strange behaviour for any browser. That's the reason I've been going on checking the Profiles>Extension folder, but indeed is empty. I checked if Firefox moves folders/files it deletes to the Recycle Bin. But none of those were in the Bin.

I have been checking files and folders, anything having extensions in it, basically because I don't fully remember the latest set of extensions that I was using. Atleast if I knew what I had been using, I could re-install them. And yes, the painful thing is that all the data and the settings pertaining to that Extension would also have been deleted autocratically by Firefox. And ok, I'll have to build it all up again, but atleast I could give it a shot. But now, even the list of extensions is gone, extensions that I have filtered and settled on, after trying out several similar.

Firefox when it takes us totally by surprise, and deletes stuff in this high-minded manner, it does not leave any possibility of roll-back, or even re-installing to the same environment.

We'll just have to live with it, and pick up our pieces, and build everything again. But that is it. I am done with updating Firefox automatically ever. And if I do it manually, I'll ensure that everything is duplicated and copied somewhere, where I can throw out the new install, and restore back to where I was.

P.S. I did compare the Profiles folder against the about:profiles page. All 3 profiles listed in the About:Profiles were there in the Profiles folder. There were 2 other even more older Profile folders, that did not show in the About:Profiles page.

Thanks so much for volunteering and putting in this effort. I am sorry I couldn't reply earlier, as I was tied up with this renovation work.

If you check the prefs.js file or about:config, do you still have a lot of data in this preference:

extensions.webextensions.uuids

That should list the extension of IDs of the extension you have had installed in this profile over time. The format is along these lines:

..., "window-autonumber@jeffersonscher.com":"a90def39-c9e2-4b49-8382-03d4685d80a7", {73a6fe31-595d-460b-a920-fcc0f8843232}":"bf87dc7f-8758-444e-9523-3addd574ba17", ...

The quoted string before the : is the public ID, and the quoted string after the : is the local unique ID, which you can ignore unless you need to research old storage folders.

Many IDs are hard to track down through a web search. I have a page you can use to lookup public IDs on the Mozilla Add-ons site (AMO). If there isn't a result, the extension might have been a legacy extension from before Firefox 57 or not distributed through AMO.

https://www.jeffersonscher.com/sumo/extensions.html

Thanks so much Jefferson. So great we have people like you to help out when Mozilla messes us up.

I took your advice. I thought this would be something too tech, and put it for later. But then once I just followed your instructions, it wasn't bad at all.

Below was my Data under the Preference "{"doh-rollout@mozilla.org":"f9d4d37a-726a-4dae-8e72-e585c34dd31c","formautofill@mozilla.org":"e56ceb22-bb4a-49a7-a7a7-0ca44b48182f","screenshots@mozilla.org":"af4a79be-7146-4abb-9507-3667d34515fe","webcompat-reporter@mozilla.org":"4f95c0a2-72dc-43b3-b012-55e65fd08e23","webcompat@mozilla.org":"e538d224-4be1-4ac5-8055-6d3529b6d2ed","default-theme@mozilla.org":"a736bd95-0cb0-43ea-9e66-019b25dd7ed3","firefox-compact-dark@mozilla.org":"2fe33907-3fb1-4f3d-a9f5-1d1851f653e4","abb@amazon.com":"e203fa01-ad90-4020-91c6-ec2804d11390","addon@darkreader.org":"19e61026-6e2e-4530-91cc-840aa90c9659","amptra@keepa.com":"00a3d1cb-b0c9-4210-b1e2-c5fd026eb02d","jid1-93CWPmRbVPjRQA@jetpack":"d47a9445-0b0b-4bb9-922d-d18044b1c762","jid1-Kt2kYYgi32zPuw@jetpack":"2457d61b-76d1-4c64-818e-cfb10a5d03de","multipletab@piro.sakura.ne.jp":"27500b1e-9e62-42ce-a287-5b7bc53f7bfb","Tab-Session-Manager@sienori":"fd8dcaa0-f300-4269-a1c8-0cbcd79eb36b","treestyletab@piro.sakura.ne.jp":"93f20a3a-508e-4eb5-bca7-b1d69fb71c69","{b9db16a4-6edc-47ec-a1f4-b86292ed211d}":"ded22155-f1bd-40d0-9c72-ac8f5b679730","uBlock0@raymondhill.net":"be5bb304-3848-4be3-80de-11026dde8724","linkgopher@oooninja.com":"6f3f1ec3-e677-423e-b2ed-756f9d54a484","{b4e464f6-d082-4d25-9098-df06d39eb3e3}":"861450bd-7c6e-4bb5-96ef-6ca535661eee","jid1-ZAdIEUB7XOzOJw@jetpack":"1c2e38c0-0878-4ddf-82d7-b3e998d562b8","reset-search-defaults@mozilla.com":"cfeb01fd-563e-48ff-a86d-ee7b4f398828","pictureinpicture@mozilla.org":"d735b70c-c871-47ec-a181-93a439c70757","addons-search-detection@mozilla.com":"fd381fa2-4ffd-4f56-8055-c5fdd03ff9b1","@DuoKeyboard":"af719a59-75ac-4a25-8625-c8059fbd0652","{d8d0bc2b-45c2-404d-bb00-ce54305fc39c}":"2f1375b2-5248-4896-9d21-ed831c4f6737","proxy-failover@mozilla.com":"d9d9176e-6b45-4e85-a971-bc3b3f559ee5","tab-mover@code.guido-berhoerster.org":"205aacf0-46f5-4e1e-8367-4e57eed3b559","{6a65273e-2b26-40f5-b66e-8eed317307da}":"ed47ccbe-b730-4806-8099-4586d00aa5b6","{c2c003ee-bd69-42a2-b0e9-6f34222cb046}":"3e3d1f8c-c5ef-42c7-865b-56d461379498","extension@one-tab.com":"eefb3596-a202-4b82-a4e1-261193b57d86","{8419486a-54e9-11e8-9401-ac9e17909436}":"4eddb9c1-e475-4883-95d3-6ad3770e2c7c"}"

The webpage you gave to help me lookup - I probably didn't know to use it properly, and so didn't get any result from it. But I used a combination of Google Search and the following webpage https://www.systemlookup.com/lists.php?list=13&type=filename&search=%7B8419486a-54e9-11e8-9401-ac9e17909436%7D&s=

There were only 2 GUID's for which I could not trace a result. They were: {b4e464f6-d082-4d25-9098-df06d39eb3e3} {8419486a-54e9-11e8-9401-ac9e17909436}

But I got my most important Add-ons back, and strangely those add-ons didn't lose the data they originally had. Like the Tab Session Manager had all my previous Sessions, and the One Tab add-on also had the previous Tabs that I had reduced to One-Tab.

So, I got back all I lost, and without your help, I am not sure if I could have done that. Thanks very very much.

I don't see any results for those other two GUIDs, either. This could indicate that they were removed from the Add-ons site by their authors, or by Mozilla for various reasons, or they were bundled with some other software (distributed privately) and that's why they aren't on the Add-ons site.