Did you refresh (reset) Firefox during your update and created a new profile?

This could happen if Firefox reported that it was starting slowly.

When you refresh/reset Firefox then a new profile is created and some personal data (bookmarks, history, cookies, passwords, form data) is automatically imported. The current profile folder will be moved to an "Old Firefox Data" folder on the desktop. Installed extensions and other customizations (toolbars, prefs) that you have made are lost and need to be redone.

It is possible to recover data from the "Old Firefox Data" folder on the desktop, but be cautious not to copy corrupted files to avoid carrying over problems.

• https://support.mozilla.org/kb/Recovering+important+data+from+an+old+profile

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox
• http://kb.mozillazine.org/Recovering_a_missing_profile

These can't get your data back, but will help in the future.

These add-ons can be a great help by backing up and restoring Firefox

FEBE (Firefox Environment Backup Extension) {web link} FEBE allows you to quickly and easily backup your Firefox extensions, history, passwords, and more. In fact, it goes beyond just backing up -- It will actually rebuild your saved files individually into installable .xpi files. It will also make backup of files that you choose.

OPIE {web link} Import/Export extension preferences