How to Refresh Firefox to Fix Crashes, Bugs, and More: 3 Methods

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Learn how to reset Firefox when it isn't working as intended
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Many Firefox crashes and bugs can be caused by add-ons or changed settings. Resetting Firefox (officially called "refreshing") will fix most of these problems. You can restore some of your lost information with a little extra work or change your preferred settings manually—and this wikiHow guide will show you exactly how to do it on both Windows and Mac. We’ll also cover what, exactly, refreshing Firefox does —and when you should do it . Let’s get started!

Quick Steps for Refreshing Your Firefox Browser

  1. Open a new Firefox tab.
  2. Type " about:support " in the address bar and press Enter .
  3. Click Refresh Firefox... in the upper-right corner.
  4. Click Refresh Firefox again.
  5. Click Finish to confirm that you want to reset your browser.
  6. Delete the "Old Firefox Data" folder on your desktop.
Section 1 of 6:

Refreshing (Resetting) Firefox

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  1. Open a new Firefox tab and enter about:support in the address bar. You’ll reach a page titled “Troubleshooting Information.” Alternatively, you can reach this page by clicking ≡ (in the top right corner of the page) → Help → More troubleshooting information }}. [1]
    • If this doesn't work, click this link , then click Solution 1 .
  2. Look for the Refresh Firefox... button on the upper right side of the Troubleshooting Information page. [2]
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  3. Click the red Refresh Firefox button when it appears in the pop-up window, then Finish in the second pop-up window. This will quit and reopen Firefox, with the following changes: [3]
    • All your extensions, themes, and added search engines will be deleted.
    • All settings will be restored to their original state. This includes button placement and plugin preferences.
    • Your download history will be cleared, so make sure you know where to find your downloaded files.
  4. After you complete the Firefox reset, you’ll land on a page with the header “Success!” (letting you know the process was completed successfully). You’ll have two options on this page: to restore all windows and tabs, or restore only the ones you want. Select the option you want, then click the Let’s go! button below. [4]
    • You can also delete the old data that was removed during the reset. It’ll be stored on your desktop in a folder called “Old Firefox Data.”
    • Firefox encourages users to delete this folder if it isn’t needed anymore, since it contains sensitive information.
    • If you want to try to restore some of your old settings, see the instructions below first.
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Section 2 of 6:

Resetting Firefox When It Won’t Open

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  1. This will let you reset Firefox even if it won't open without crashing. Follow the instructions below, based on your operating system: [5]
    • Windows: Hold down ⇧ Shift while opening Firefox. If this doesn't work, search your computer for a "Mozilla Firefox (Safe Mode)" shortcut.
    • Mac: Hold down option while opening Firefox.
    • Linux: Run /path/to/firefox/firefox -safe-mode from Terminal.
  2. If a list of profiles appears, hold down the same key while clicking your profile. This will only happen if you have more than one profile.
  3. Before the Firefox browser window appears, a pop-up with two items should appear. Select Refresh Firefox to reset your settings and delete all add-ons. This is a permanent change.
    • Alternatively, select Start in Safe Mode to see if that solves the problem for this session. If it does, try disabling some add-ons and restarting Firefox normally. If it doesn't, start again in safe mode and reset Firefox.
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Section 3 of 6:

Deleting Your Firefox Preference Files

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  1. 1
    Access the Troubleshooting Information page. Resetting your Firefox preferences (which includes tabs, privacy, network, zoom, and where file downloads are saved) can help clear up issues if you’re still troubleshooting. To begin, you’ll need to get to the Troubleshooting Information page by typing about:support in the address bar. [6]
  2. 2
    Open your Profile Folder. Scroll down to the Application Basics section and look for the Profile Folder listing. Then, click on the Show in Folder button next to Profile Folder. This will open a window with your Firefox profile folder!
  3. You should always close Firefox before you change its profile settings.
  4. 4
    Delete your preferences from the profile folder. Find a file called prefs.js and delete it—this is all of your Firefox preferences. If you want to save it as a backup, you can rename it instead of deleting it. You may find more than one preferences file (like prefs.js.moztmp, or user.js , for example); if so, delete or rename those files, too. [7]
    • When you’re done, just close out the profile folder and reopen Firefox. You’re all set!
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Section 4 of 6:

Restoring Your Data After a Firefox Reset

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  1. You can use this section to restore search engines, website-specific settings, and download preferences, which don’t typically cause bugs. Your saved passwords, bookmarks, browsing history, and cookies should be restored automatically. If these are missing, you may still be able to retrieve them using these instructions.
    • If you want to restore your add-ons or settings, change them manually instead of using this guide. Restoring them from the backup will most likely recreate your old bugs.
  2. Enter about:support in the address bar, or click ≡ → ? → Troubleshooting information .
  3. You can find the folder containing your profile data by clicking a button near the top of the page. Look for the following words, depending on your system and Firefox version: [8]
    • Windows: Show Folder
    • Mac: Show in Finder
    • Linux: Open Directory
    • Firefox 13 or earlier (any OS): Open Containing Folder
  4. Your old data from before the reset should be saved in a folder on your desktop called “Old Firefox Data.” If you can't find it, search your computer the “Old Firefox Data” folder. [9]
    • On Windows, you may need to show hidden files.
  5. You should always close Firefox before you change its profile settings.
  6. Open "Old Firefox Data" and choose a file you wish to transfer (we’ll show you how to identify them in the next step). Right-click the file and select Copy . Open your new profile folder. Right-click on any blank space inside the folder and select Paste . [10]
    • On a Mac, hold down Ctrl and click the file to "right-click."
    • If prompted, choose to replace or overwrite existing files.
  7. It's best to move as few files as possible, since one of them could be responsible for the bug. Here are some suggested files to transfer: [11]
    • search.json — your added search engines
    • permissions.sqlite — preferences for which websites are allowed to store cookies, open popup windows, etc.
    • mimeTypes.rdf — preferences for handling downloaded files (which program opens which file type)
    • Firefox attempts to automatically restore the items below. You do not need to restore them yourself unless an error occurred during the reset.
      • places.sqlite — bookmarks and browsing history
      • key3.db and logins.json — saved passwords
      • formhistory.sqlite — autofill information for online forms
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Section 5 of 6:

When should you refresh Firefox?

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  1. Generally, it’s a good idea to refresh (reset) Firefox on your computer if you run into an error or performance is being drastically slowed. More specifically, consider refreshing Firefox if you run into any of the following issues:
    • You encounter internal errors or crashes
    • You have external ads and blinking pop-ups that you don’t want
    • You want to disable any harmful extensions affecting Firefox
    • You encounter issues with freezing or a slowed-down system performance
    • Your homepage redirects to policy settings
Section 6 of 6:

What does refreshing Firefox do?

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  1. Refreshing Firefox returns it to its default state while saving your settings. When you refresh Firefox, it stores your settings and information in a folder on your desktop, while creating a new profile folder with just your most important data. Refreshing also removes any add-ons inside the Firefox profile folder, including extensions and themes. However, if you have add-ons stored outside the Firefox profile folder, those won’t be removed.
    • During a Firefox reset, your bookmarks, browsing and download history, passwords, cookies, web form autofill information, and personal dictionary will all be saved .
    • Any extensions and themes, website permissions, modified preferences, added search engines, DOM storage, security certificate, and device settings, download actions, toolbar customizations, and user styles will be removed .
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      References

      1. ↑ https://support.mozilla.org/en-US/kb/use-troubleshooting-information-page-fix-firefox
      2. ↑ https://youtu.be/v4PQn0kPB88?t=26
      3. ↑ https://support.mozilla.org/en-US/kb/refresh-firefox-reset-add-ons-and-settings
      4. ↑ https://youtu.be/v4PQn0kPB88?t=47
      5. ↑ https://kb.mozillazine.org/Safe_Mode#All_systems
      6. ↑ https://support.mozilla.org/en-US/kb/reset-preferences-fix-problems
      7. ↑ https://support.mozilla.org/en-US/kb/reset-preferences-fix-problems
      8. ↑ https://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox
      9. ↑ https://support.mozilla.org/en-US/kb/refresh-firefox-reset-add-ons-and-settings
      1. ↑ https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile
      2. ↑ https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

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