If you haven't already, before doing any file moves/deletes/reinstalls, you may want to do a normal system shutdown and startup to release any file locks and complete any pending updates. One user reported it took three shutdown/restarts to sort out his issues.

If your data does not magically reappear, the most likely scenarios for complete data loss are:

(1) A Refresh started but the migration of data from your old profile to your new profile was incomplete, or

(2) Your old profile was locked, so Firefox ignored it and created a new one.

Here's how to investigate those two possibilities:

Did Firefox perform a Refresh?

Unless it was interrupted in progress, you should find a folder on your desktop named Old Firefox Data. Inside would be a semi-randomly-named folder with freshly updated files. Do you see anything like that?

If so, we'll suggest how to rescue key files or completely restore the earlier profile folder.

If not...

Does the Profile Manager list your immediately previous profile folder?

To check on that, inside Firefox, type or paste about:profiles in the address bar and press Enter/Return to load it.

This page should list all the profiles Firefox is currently aware of. If you see a profile that is not currently set as default that looks promising, 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 I think those are still "under construction" so please ignore them.)

Firefox should exit and then start up using the other profile. Is that the right one?

If it's not there...

Did Firefox orphan your old profile folder?

Here's how to check whether there are additional profile folders in the standard location in addition to the one you're using. Start by opening your current 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/Return

In the first table on the page, click:

* Windows: the "Open Folder" button, to launch a new window listing various files and folders in Windows Explorer.
* Mac: the "Show in Finder" button, to launch a new window listing various files and folders in Finder.

In the Windows Explorer address bar, click the capitalized word Profiles to move up one level in the folder hierarchy. More than one folder here by any chance? Do the files in those folders look like they were last updated around the time of the update?

(Mac users: please do what you need to do in Finder to check up one level...)

If you've got any promising looking folders, we can discuss next steps to recover use of them.

Note that current Firefox releases use a compressed .jsonlz4 for the automatically created backups in the bookmarkbackups folder.

It is possible that there has been a problem with the profiles.ini file that registers profiles and that a new default profile got created.

You can check if you have orphaned profiles that aren't registered in profiles.ini and that do not show in the Firefox Profile Manager. You can check that by opening the current profile folder and go up one level.

• http://kb.mozillazine.org/profiles.ini_file

If you have found an orphaned profile then you may want to recover some personal data.

• C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\Profiles\<profile>\

"AppData" (XP: Application Data; Mac: ~/Library; Linux: ~/.mozilla) is a hidden folder.

• http://kb.mozillazine.org/Show_hidden_files_and_folders

You can check whether you have an "Old Firefox Data" folder on the desktop in case the Refresh feature in Firefox has been used and a new profile has been created.

See also:

• 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