I think a lot of us have fallen for that at some point.

"Reset" would be a better word to use, as well as there being a clear explicit warning of what it will do. "Refresh" implies things like clearing the cache and expired cookies, not stuff that will pretty obviously be wanted again.

It's even worse if you only use Firefox occasionally as then when you do it will pop-up a message pointing out that you having used it for a while asking if you'd like to "Refresh" it. That's how I learnt what it does.

Firefox's Refresh/Reset feature preserves your original profile folder and moves it to your desktop inside an Old Firefox Data folder. So it is possible to copy/paste some things and roll back the change if you want to. There are some steps:

Option #1: Copy/paste individual files. See: Recovering important data from an old profile

Option #2: Wholesale transplant - not officially supported but here's how if you want to try:

(1) Open Source Old Firefox Data Folder

Open the Old Firefox Data folder on your desktop. Do not drill down into any subfolders.

Resize that File Explorer window with the source folder and move it to the left side of the screen.

(2) Open Destination Profiles Folder

Open the receiving Profiles folder using either step-by-navigation, or by pasting a shortcut in the Windows 10/11 system search box and pressing Enter to launch it:

• C:\Users\username\AppData\Roaming\Mozilla\Firefox\Profiles
• Shortcut: %APPDATA%\Mozilla\Firefox\Profiles

(You may need to set Windows to show hidden files and folders: https://support.microsoft.com/en-us/windows/view-hidden-files-and-folders-in-windows-97fbc472-c603-9d90-91d0-1166d1d9f4b5)

Resize that File Explorer window with the destination folder and move it to the right side of the screen.

(3) Drop a copy of the old profile folder back into the folder Firefox uses for profiles:

In the source Old Firefox Data folder on the left, right-click the profile folder and choose Copy. Important: copy the folder because you need to transfer the folder. This is not a method where you copy individual files.

In the destination Profiles folder on the right side of the screen, right-click an empty area and choose Paste to paste the folder here.

(4) Configure Firefox to use the old profile

Make a note of the text after the dot on the profile folder. For example, it might be default or default-release. You need the new profile name to match the old one in order for Firefox to regain use of your extensions and their data.

Inside Firefox, type or paste about:profiles in the address bar and press Enter/Return to load it.

• Click the "Create a New Profile" button, then click Next.
• Assign the old profile name default and Firefox should show a proposed folder name with a new random part.
• Click the "Choose Folder..." button, then if needed, navigate to the Profiles folder, and then select the old profile folder you copy/pasted so that Firefox picks up the full old name.
• Back in Firefox, click the Done button.

After creating a new profile, Firefox usually makes it your default profile (for external links and the next startup). To test, scroll down to it and click the Launch profile in new browser button.

Did it work?

If so, you're done.

If not, you can close that window without affecting your regular Firefox profile and change back to the profile you started with before this post. Click the Set as Default Profile button below that profile.

This could have proved helpful but my profile from before the 'refresh' that reset the browser had not been saved and I had important all the synced data. The problem is that OneTab saves its data in a temporary form, out of safety and privacy concerns I assume. Which is fine so long as the browser or the user don't uninstall the extension. I tried following the instructions and I just find a blank profile with nothing.

But thanks for trying.

Old Firefox Data has a profile folder inside but it's empty? Hmm... could you try this:

(1) Find out your current profile name. On about:profiles, it's the one with "This is the profile in use and it cannot be deleted."

On the right end is a dash and a date/time code. The part to the left is the part that would match your old profile name.

(2) Return to the Profiles folder at

C:\Users\username\AppData\Roaming\Mozilla\Firefox\Profiles

Is the old profile folder still there -- Firefox failed to move it to the Old Firefox Data folder?

By the way, most add-ons that store large amounts of data use purely local storage due to strict limits on how much data add-ons are allowed to sync. Definitely a problem with OneTab and other session managers.

I agree, the extension is really useful and I've not found one that does the same role but it has a really fatal flaw. I try to save the data manually on the regular but it had been so long without any issues or risks that I had not paid attention.

Old Firefox Data has a profile folder inside but it's empty? Hmm... could you try this: (1) Find out your current profile name. On about:profiles, it's the one with "This is the profile in use and it cannot be deleted." On the right end is a dash and a date/time code. The part to the left is the part that would match your old profile name. (2) Return to the Profiles folder at C:\Users\username\AppData\Roaming\Mozilla\Firefox\Profiles Is the old profile folder still there -- Firefox failed to move it to the Old Firefox Data folder?

Now the folder isn't empty because I used the about:profile to open the other profile to see if it had kept anything saved but when I opened the old profile it had no extensions installed and no bookmarks, thus no data saved at all. There was no information saved, no.

When you say the other profile, do you mean the one named default? If you started with Firefox version 67 or later on this computer, that profile usually doesn't contain anything and can be ignored. Instead, the one named default-release is the important one. Each time you use Refresh, the profile is cloned and cleaned and a date/time-stamp is added to the name, and the old default-release folder moved to Old Firefox Data on your Windows desktop. It's weird that the moved folder is empty. That doesn't make any sense.

Depending on how far back it would be useful to go, you could consider looking into shadow copies of your profile saved by Windows when it does automatic updates. To check what is available, try the following steps:

(1) Set Windows to show hidden files and folders, if you haven't done this before:

https://support.microsoft.com/en-us/windows/view-hidden-files-and-folders-in-windows-97fbc472-c603-9d90-91d0-1166d1d9f4b5

(2) Download and install one of the following programs:

• ShadowExplorer: http://www.shadowexplorer.com/
• Shadow Copy View: https://www.nirsoft.net/utils/shadow_copy_view.html

(3) Start up the program and look for the latest restore point. Then explore along this path to see whether you can find a shadow copy of your profile:

\Users\your-user-name\AppData\Roaming\Mozilla\Firefox\Profiles\your.profile

(4) Export out the prefs.js file to your Windows desktop, then open it in a tab in Firefox. Use Find in Page (Ctrl+F) to search for one-tab.com and Firefox should jump to a messy part of the page. This will have text along the lines of:

\"extension@one-tab.com\":\"73c2af4b-abcd-6789-fa44-4c93e23843e4\"

That second value is a unique, locally generated ID used to name the OneTab storage folder.

(5) Back in the shadow copy, expand the storage folder, then the default folder, then find the folder starting with moz-extension+++ that matches the unique ID. This is your OneTab data.

As for how best to work with it, I'm not sure. You could export out this folder, then drop it into your post-Refresh profile under the new OneTab folder (check the about:debugging page to find the new unique local ID for that folder). I've never tested to make sure that works.