Hi Dorian, just to confirm, it's Windows now and a Windows drive, this isn't a Mac-reading-Windows scenario? (Because I would be very confused about that...)

Let's start with checking that your old data is intact.

Make sure Windows is set 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

Next, on your old drive, which I'll refer to as the "E" drive (but substitute whatever it actually is) explore up this path:

E:\Users\<username>\AppData\Roaming\Mozilla\Firefox\Profiles

Here you should find at least one folder and there may be several. So far so good?

If your new drive isn't up and running, you may want to back up the entire Firefox folder somewhere safe for future reference.

Option #1: File-by-file restoration

Bookmarks are the best supported. Within each profile folder within Firefox\Profiles, double-click into the bookmarkbackups folder to see which one has the most recent files -- the creation dates are coded into the file names.

Right-click > Copy one or two promising candidates and then right-click > Paste to the currently live desktop (not the desktop on the old drive).

You can restore those bookmarks using the steps in the following article -- using the "Choose File" option to point Firefox to the desktop where you pasted the backup.

Restore bookmarks from backup or move them to another computer

You can selectively restore other files by manually replacing new files with old ones. See this article for more information on key files: Recovering important data from an old profile.

Option #2: Full Restore

While this is not officially supported, if your Windows username will be the same, this "transplant" process has worked for some users who reported back (others might have found it too complicated and never confirmed):

(1) Open Source Firefox\Profiles Folder

E:\Users\<username>\AppData\Roaming\Mozilla\Firefox\Profiles

Do not drill down into any subfolders, but know which one you want to restore.

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 system search box and pressing Enter to launch it:

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

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 and Firefox should show a proposed folder name with a new random part.
• Click the "Choose Folder..." button and 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.

See also:

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

You can copy certain files with Firefox closed from the profile folder to backup your personal data. Note that best is to avoid restoring a full profile folder and only restore important files that are safe to restore/transfer.

• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

• bookmarks and history: places.sqlite
• favicons: favicons.sqlite
• bookmark backups: compressed .jsonlz4 JSON backups in the bookmarkbackups folder
• cookies.sqlite for the Cookies
• formhistory.sqlite for saved autocomplete Form Data
• logins.json (encrypted logins) and key4.db (encryption key and primary password) for logins saved in the Password Manager
• cert9.db for certificates stored in the Certificate Manager
• persdict.dat for words added to the spell checker dictionary
• permissions.sqlite for Permissions and possibly content-prefs.sqlite for other website specific data (Site Preferences)
• sessionstore.jsonlz4 for open tabs and pinned tabs (see also the sessionstore-backups folder)

Hello jscher 2000, First of all thank you so much for your detailed explanation and l.inks. I really had one problem chasing the next! But at least I found a backup 4 month old and was able to restore. But then..... 4 month of data missing. I was able to copy the data from the busted Windows to an other disk, only to wreck that disk.... meaning could not enter anymore. So I bought an expensive recovery software to look at the data. Just this morning I was able to look into the disk again and under App Data/Roaming I found some Bookmarks Folder which I copied into an other disk. This I all did on the Mac because the restore Software is there. I just hope that I got all the bookmarks. I also found a places.sqlite and favions.sqlite which I also saved. Hope this will be enough to restore my bookmarks.

Regards Dorian