See Creating a profile :

• https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over the problem. Never work with original files.

• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data
• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile
• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

Please uninstall Flash 25.0 r0, it is a security risk by the 100. Flash Player Version: 28.0.0.126 Current Version

• https://get.adobe.com/flashplayer/otherversions/

Step 1: Select Operating System Step 2: Select A Version (Firefox, . . . .) Note: Other software is offered in the download. <Windows Only>

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

If you use external cleanup software like CCleaner then check the settings for Firefox. You can also check if you have such software scheduled to run at the time you lose the history.

In Firefox usually only the "Clear history when Firefox closes" matters. To see all History and Cookie settings, choose:

• Options/Preferences -> Privacy & Security -> Firefox will: "Use custom settings for history"
• https://support.mozilla.org/en-US/kb/Options+window+-+Privacy+panel

You can check for problems with the places.sqlite database (bookmarks and history) in the Firefox profile folder.

• use "Verify Integrity" on the "Help -> Troubleshooting Information" (about:support) page
• https://addons.mozilla.org/firefox/addon/places-maintenance/

See also:

• http://kb.mozillazine.org/Locked_or_damaged_places.sqlite
• https://support.mozilla.org/en-US/kb/Bookmarks+not+saved#w_fix-the-bookmarks-file

Sorry to hear about your data loss. Did you lose any other data or settings during the upgrade?

Did your Firefox perform a Refresh and move your old data to your desktop inside an Old Firefox Data folder? If so, hang onto that since it may be useful for finding old history.

Mining Restore Points for Old places.sqlite Files (Windows 7)

You may also want to check old Windows Restore Points for copies of your places.sqlite file. Do not use the Windows System Restore feature as that may make the situation worse. The method I am about to describe is much safer.

Open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" button > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, next to Profile Folder, click the "Open Folder" button. This should launch a new window listing various files and folders in Windows Explorer.

Scroll down and right-click places.sqlite and choose Properties. In the Properties dialog, click the Previous Versions tab. Windows will search for copies of places.sqlite in restore points from system updates. You can select an older file and use the Copy button to copy it to a neutral location such as your Desktop or Documents folder, where Firefox won't overwrite it.

If you find any files worth testing out, here's what I suggest next:

Examine Old places.sqlite File in a New Profile

To avoid disrupting your current Firefox setup, create a new profile in parallel to your current one.

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 a name like Dec2017, ignore the option to relocate the profile folder, and click the Finish button.

After creating the profile, scroll down to it and click the Set as default profile button below that profile, then scroll back up and click the Restart normally button. (There are some other buttons, but please ignore them.)

Firefox should exit and then start up using the new profile, which will just look brand new.

Now we're going to replace the places.sqlite database in this profile with the old one to see what's in it. In order to do that, we need to (A) open the new profile folder and (B) exit out of Firefox.

Open the about:profiles page and scan down the page for "This is the profile in use and it cannot be deleted." On the line that says Root Directory, click the Open Folder button. You should find a places.sqlite file in this folder.

Exit out of Firefox. Then you can replace the new places.sqlite in that profile folder with the old one you extracted from the restore point. When you start Firefox, it hopefully will accept the database and show you the old history. Can you find the long-lost address?

When you are done with the experiment, open the about:profiles page again, click the Set as default profile button for your normal profile, then click the Restart normally button to get back to it.