If you are having a problem with Firefox then sometimes, rather than trying to find and fix the exact cause of the problem, it is easier just to make a new Firefox profile and copy your most important data over to it.

A Firefox profile stores all your important data, such as your bookmarks, history, passwords, etc. Making a new Firefox profile and then copying over certain files gives you a fresh start while retaining your important personal data.

Table Of Contents

• Back up your current profile
• Create a new Firefox profile
• Copying files between profile folders
• Your important data and their files
• Bookmarks and Browsing History
• Bookmarks
• Passwords
• Site-specific preferences
• Search engines
• Personal dictionary
• Autocomplete history
• Cookies
• Browsing history
• Security certificate settings
• Download actions
• User styles

Back up your current profile

Before starting it is recommended that you make a complete backup of your existing Firefox profile in case something goes wrong. Please read the Backing up your information article for how to do this.

Create a new Firefox profile

For information on how to create a brand new Firefox profile, please read the Managing profiles article, paying specific attention to the Creating a profile section.

Copying files between profile folders

Note: Firefox must be closed down while copying files between profile folders.

1. From the menu at the top of the Firefox windowbar, select FileFirefox and then select the ExitQuit FirefoxQuit menu item.
2. Locate your old Firefox profile folder. Read How to find your profile folder for information on how to do this.
3. On a file you want to copy, right click and choose Copy.
4. Locate your new Firefox profile folder.
5. Right click on the area and choose Paste Item.

Repeat steps 2-5 for each file you wish to transfer over to your new profile folder.

While copying your personal data from an old Firefox profile to a new Firefox profile, it is possible that you could copy over the file that is causing the problem you are trying to get rid of! The more files you copy over, the greater the chance of this happening. It is therefore recommended that:

• You copy over only the minimal amount of files that contain your most important data that you simply can't live without.
• You copy over a few files at a time, and then check that the problem you are trying to get rid of hasn't returned.

Your important data and their files

Passwords

Site-specific preferences

This file stores many of your Firefox permissions that are decided on a per-site basis. For example, it stores which sites are allowed to, or blocked from setting cookies, installing extensions, showing images, displaying popups, etc.

Search engines

• search.sqlite
• \searchplugins\ folder

If you have installed any extra search engines then they will be in the \searchplugins\ folder. The search.sqlite file stores the order that your search engines appear in Firefox. For more information see Search bar.

Personal dictionary

• persdict.dat

This file stores any custom words you have added to Firefox's dictionary. If you have never added a custom word to the Firefox dictionary, then you will not have this file. For more information see Using the spell checker.

Autocomplete history

This file remembers what you have searched for in the Firefox search bar and what information you have entered into forms on web sites. For more information see Form autocomplete.

Cookies

Cookies are used by web sites for a variety of reasons, some of which include keeping you logged into a web site you have previously logged into, remembering any preferences a web site has allowed you to set, authenticating you as a person who has visited a specific web site before, etc. For more information see Cookies.

Security certificate settings

• cert8.db

This file stores all your security certificate settings and any SSL certificates you have imported into Firefox.

Download actions

• mimeTypes.rdf

This file stores your preferences with respect to what Firefox does when it comes across known file types. For more information see Managing file types.

User styles

• \chrome\userChrome.css
• \chrome\userContent.css

If they exist, these two files store user-defined changes to either how Firefox looks, or how certain web sites or html elements look or act. Most people will not have these files. You may have two files in the \chrome\ folder called userChrome-example.css and userContent-example.css, but both these files can be safely ignored.

Based on information from Transferring data to a new profile - Firefox (mozillaZine KB)