Did you use the Refresh feature in Firefox and have created new profile? When you use the Firefox Refresh feature then a new profile is created and some personal data (bookmarks, history, cookies, passwords, form data, tabs) 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. You can copy files like these to the current Firefox profile folder to recover specific data. *bookmarks and history: places.sqlite *bookmark backups: JSON backups in the bookmarkbackups folder *SQLite files like cookies.sqlite (cookies) and formhistory.sqlite (saved form data) *logins.json and key3.db (decryption key) for Passwords saved in the Password Manager *cert8.db and possibly cert_override.txt for (intermediate) certificates stored in the Certificate Manager *persdict.dat for words you added to the spelling checker dictionary *permissions.sqlite for Permissions and possibly content-prefs.sqlite for other Site Preferences *sessionstore.js for open tabs and pinned tabs and tab groups You can use this button to go to the current Firefox profile folder: *Help > Troubleshooting Information > Profile Directory:<br>Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder *http://kb.mozillazine.org/Profile_folder_-_Firefox ---- If you didn't create a new profile and the extensions folder in the current profile still has the extensions then it is possible that there is a problem with files in the profile folder that store the extensions registry. Delete the extensions.* files (e.g. extensions.json, extensions.ini, extensions.sqlite) and compatibility.ini in the Firefox profile folder to reset the extensions registry. *https://support.mozilla.org/kb/Profiles New files will be created when required. See "Corrupt extension files": *http://kb.mozillazine.org/Unable_to_install_themes_or_extensions *https://support.mozilla.org/kb/Unable+to+install+add-ons If you see disabled or not compatible extensions in "3-bar button/Tools > Add-ons > Extensions" then click the Tools button at the left end of the Search bar to check if there is a compatibility update available. If this didn't help then delete Add-ons.json and possibly prefs.js in case there is a problem with preferences.