PROBLEM SOLUTION:ĭon’t worry! You have not lost any browser data. They are still stored in your browser and computer but since Firefox is using a clean profile, it’s not showing them by default. So your bookmarks, add-ons and settings are not gone or lost. That’s why it created a fresh new blank user profile and started using it. When you upgraded to latest version of Firefox, it detected an existing profile which was also used by another version of Firefox. That’s why to overcome this issue, now newer versions of Firefox come with this new functionality built-in. Firefox protects you against running older versions of the browser which can lead to data corruption and stability issues. That’s the reason behind Firefox showing you “You’ve launched an older version of Firefox” error message at startup. Sharing same user profile among all Firefox installations also caused profile corruption and browser crashes issues.

In older versions of Firefox, a single user profile was shared by all Firefox versions and users were unable to run different Firefox versions side-by-side simultaneously.

This new feature allows users to install different versions of Firefox (such as stable, beta, nightly, developer and ESR) in their computers and use them side-by-side with dedicated or separate profiles for each Firefox version. It’s happening because Firefox upgraded to recently released version 67 or later which comes with a new feature called “ Dedicated Profiles per Firefox Installation Architecture“. When you click on “OK” button, Firefox closes. Now you are forced to use Firefox from scratch and you’ll have to customize all settings, add bookmarks and install add-ons again.įirefox started showing following error message at startup: You can’t find your bookmarked websites and installed add-ons in Firefox. All your bookmarks, add-ons and custom settings lost/vanished/disappeared. In other words, Firefox opened like you performed a clean installation of Firefox in your computer.

You installed several add-ons (extensions, themes, dictionaries, language packs) to add new functionality and features to Firefox.Įverything was working perfectly and suddenly one day when you launched Firefox: You added your favorite websites and webpages as bookmarks for quick and easy access. You customized Firefox Settings (also known as Options or Preferences) and UI according to your requirements. You were using Mozilla Firefox web browser in your computer since few days, months or years without any problem.

How to get older versions of firefox