Refresh Firefox: Preserved vs. Discarded User Data

The "Refresh Firefox" feature is a built-in troubleshooting tool designed to fix browser issues like slowness or crashing by restoring the browser to its default state. This article provides a direct breakdown of the exact user data that Firefox safely preserves during this process, as well as the specific customizations, settings, and add-ons that are discarded when you click the Refresh button.

User Data That is Preserved

When you refresh Firefox, it creates a brand new user profile and automatically transfers your most important personal data into it. You will not lose the following information:

  • Bookmarks: All saved bookmarks, including their folder structures and tags, remain intact.
  • Browsing and Download History: Your record of visited websites and previously downloaded files is kept.
  • Passwords: All saved login credentials stored in the Firefox Password Manager are transferred.
  • Cookies: Active website cookies are saved, keeping you logged into most of your frequented websites.
  • Web Form Auto-fill Information: Saved addresses, credit card details, and other form-fill data are preserved.
  • Personal Dictionary: Any custom words you have added to the Firefox spellchecker remain saved.
  • Open Windows and Tabs: The session you had open at the exact moment of the refresh will be restored when the browser restarts.

User Data That is Discarded

Because incorrect settings and faulty add-ons are the most common causes of browser problems, Firefox completely removes them during a refresh. The following data is discarded and reset to factory defaults:

  • Extensions and Themes: All installed add-ons, browser extensions, and visual themes are removed.
  • Website Permissions: Site-specific permissions—such as allowing or blocking access to your camera, microphone, location, or pop-ups—are wiped out.
  • Modified Preferences: Any changes made in the Firefox Settings menu or advanced tweaks made via the about:config page are reset to default.
  • Added Search Engines: Custom search engines you added to the browser are removed, leaving only the default search providers.
  • DOM Storage: Website-specific local data (similar to cookies, often used by web apps to store data offline) is cleared.
  • Security Certificate and Device Settings: Custom security certificates you have imported are removed.
  • Download Actions: Preferences detailing how Firefox should handle specific file types (e.g., always opening PDFs in a specific program) are reset.
  • Toolbar Customizations: Any changes to the layout of your buttons, toolbars, and custom userChrome.css styles are discarded.

The Desktop Backup

While the discarded data is removed from the active browser, it is not immediately deleted from your computer. When you click Refresh, Firefox places a folder on your desktop named Old Firefox Data. This folder contains your entire previous profile. If you accidentally lose a critical setting or piece of data during the refresh, you can manually recover the files from this folder and move them into your new Firefox profile. If the refresh goes smoothly, you can safely delete this folder to free up hard drive space.