Most crashes or bugs in Firefox are caused by add-ons or setting changes. Resetting Firefox, otherwise known as refreshing, will solve the problem. You can restore lost information with minimal effort, or reset your browser manually.
Step
Method 1 of 3: Resetting Firefox
Step 1. Visit the Firefox troubleshooting page by opening a new tab and entering about:support in the address bar
You will see the Troubleshooting information page.
- You can also go to the page by pressing the {button|≡}} button (usually located in the upper right corner of the screen) > ? (bottom right) > Troubleshooting information.
- If the above steps don't work, visit this link and click Solution 1.
Step 2. Click the Refresh Firefox button
.. at the top right of the screen.
Step 3. Confirm the changes
Click Refresh Firefox again in the window that appears, then click Finish in the second window. Firefox will close itself with the following changes:
- Add-ons, themes, and search engines that you added will be deleted.
- Your settings will return to the default settings, including add-on settings and button placement.
- Your download history will be deleted, so you'll need to know where you saved your downloaded files.
Step 4. Erase your old data
Mozilla recommends that you delete the directory named "Old Firefox Data." If you want to try to restore some of the settings, read the guide below first.
Method 2 of 3: Resetting a Firefox Not Open
Step 1. Open Firefox in safe mode to reset Firefox that won't open
The method is as follows:
- Windows: Hold Shift while opening Firefox. If that doesn't work, find the "Mozilla Firefox (Safe Mode)" shortcut on your computer.
- Mac: Hold down option} while opening Firefox.
- Linux: Run the command /path/to/firefox/firefox -safe-mode from Terminal.
Step 2. Hold down the same button while you select a profile
If a list of profiles appears, hold down the same button while selecting a profile. This window will only appear if you have multiple profiles in Firefox.
Step 3. Select Refresh Firefox
Before the Firefox window appears, a window with two buttons will appear. Select Refresh Firefox to reset your browser and remove all add-ons. This process cannot be undone.
You can also press the Start in Safe Mode button to see if your browser problem doesn't occur in the safe session. If your browser is working normally in safe mode, try turning off some add-ons and restarting Firefox normally. If not, restart Firefox in safe mode, and reset Firefox settings
Method 3 of 3: Restoring Data after Reset
Step 1. Check for missing data
This method allows you to restore search engine, specific website settings, and download settings, which generally don't cause errors. Saved passwords, bookmarks, browsing history, and cookies should also be returned automatically -- otherwise, you can still recover them with this guide.
If you want to restore add-ons or settings, make changes manually, instead of using this guide. Restoring data after resetting the browser will generally only bring back old problems
Step 2. Visit the Firefox troubleshooting page by opening a new tab and entering about:support in the address bar
You can also enter the page by pressing the {button+≡ (usually located in the upper right corner of the screen) > ? (bottom right) > Troubleshooting information.
Step 3. Open your profile data
You can find the data directory by clicking the button at the top of the page. Look for the following words, depending on your operating system and Firefox version:
- Windows: Show Folder
- Mac: Show in Finder
- Linux: Open Directory
- Firefox 13 or earlier, any system: Open Containing Folder
Step 4. Find your old data
Your browser data before reset should be saved in a directory on your desktop. If you can't find it, look for the "Old Firefox Data" directory on your computer.
If you are using Windows, you may need to show hidden files
Step 5. Close Firefox before making any profile changes
Step 6. Copy the file to your current profile
Open the "Old Firefox Data" directory and select the file you want to transfer. Read the bottom of this article to determine which files you should transfer. Right-click on the file and select Copy. Open your new profile directory, right-click on any empty space in the directory, and then click Paste.
- If you're using a Mac, hold down Ctrl and click the file to right-click.
- If prompted, choose to overwrite the existing file.
Step 7. Select the files you want to transfer
Move as few files as possible, as one of the files may be the cause of the Firefox error. Here are some suggested files that might be transferable:
- search.json - Contains the search engine you added.
- permissions.sqlite - Contains site settings, cookie permissions, pop-up windows, etc.
- mimeTypes.rdf - File download settings (the program used to open certain files).
- Firefox will try to restore the files below automatically. You don't need to move them manually, unless something goes wrong during the reset process.
- places.sqlite - download and browsing history.
- key3.db and logins.json - saved passwords.
- formhistory.sqlite - autofill information for online forms.
