7. Profiles & Backup

7.1. What is my profile?

Your profile is your identity in Mozilla. Your profile contains your bookmarks, mail/news files and account settings, stored passwords, address book, security certificates and preferences.

You may have multiple Mozilla profiles on one computer, for example, to separate your home and work Web surfing activities, or for each of your family members sharing your computer.

7.2. How do I set up multiple profiles?

You may set up new profiles from the Profile Manager:

  • On Windows, open the Start menu and choose Programs, then Mozilla, then Profile Manager. Or you can run mozilla -profilemanager from the command-line window.

  • On Mac OS X, hold down the Option key and double click the Mozilla icon.

  • On Linux or Unix, open a shell prompt, cd to the Mozilla program directory and enter mozilla -profilemanager

If you had a previous profile and it is not listed, it is either corrupted or is no longer recognized by Mozilla.

7.3. Where is my profile stored?

The location of a profile has three elements: the BASE, its NAME, and its SALT (xxxxxxxx.slt). For example,

C:\Windows\Application Data\Mozilla\Profiles\ John Smith\ lm34qgkq.slt
base profile directory name salt

The BASE profile directory houses the profile registry (Registry.dat) file. The BASE directory depends on the system settings, as will be described later.

When you create a new profile, you can choose a different BASE directory and NAME sub-directory to put your profile files.

The SALT is a sub-directory named with eight random alpha-numerals followed by .slt extension (see 7.4 “What is the @$%#@$%#.slt directory in my profile directory”). When you create a new profile, Mozilla automatically generates a SALT directory if it doesn't already exist. But if SALT does exist, the Profile Manager will use it.

The following lists typical base profile directories:


  • On Windows 95, Windows 98, or Windows ME (without log-in), a typical base profile location is:

    C:\Windows\Application Data\Mozilla\Profiles\
  • On Windows 95, Windows 98 or Windows ME with login, a typical base profile location is:

    C:\Windows\Profiles\[Log-in Name]\Application Data\Mozilla\Profiles\
  • On Windows 2000 or Windows XP, a typical base profile location is:

    C:\Documents and Settings\[Log-in Name]\Application Data\Mozilla\Profiles\

    Note: on Windows 2000 and Windows XP, the “Document and Settings” directory is hidden twice; to access the directory, you may need to set Windows Explorer to show System and Hidden directories and files.


  • On Mac OS X, a typical profile location is:



  • On Linux, a typical profile location is:


7.4. What is the @$%#@$%#.slt directory in my profile directory?

This is called “salting.” Profile data is stored in a randomly named directory to make it difficult for malicious programs to find profile data (see bug 56002 and 97180)

7.5. How do I move my Netscape 4.x profile to Mozilla?

The Profile Manager should detect and import a profile from Netscape 4.5 or later automatically while installing, except for the address book and any security certificates.

You can import your bookmarks by hand with Bookmarks | Manage Bookmarks | Tools | Import. Since the bookmarks file is an HTML file, it can also easily be edited by hand.

To move your address book, export it from Netscape 4.x as text (.ldif) and import it into Mozilla as LDIF.

Your mail files (the files with no extensions) can be copied directly from your Netscape 4 profile to the Mail folder in your Mozilla profile.

7.6. How do I back up my profile data?

Occasionally, your browser software or your computer system may malfunction and cause important profile data to be lost. Therefore we recommand that you make a backup copy of your profile periodically. Backup frequency will depend on your usage.

All your user data are stored in your profile directories (see 7.3 “Where is my profile stored?”). If you are not sure what to back up, or if you want to back up everything, back up the entire directory content. Restoring or transport profile data will be easier if you keep the SALT and NAME directory hierarchy.

The following subsection describes how you can selectively back up your data:


Mail messages are stored in the Mail (or ImapMail) sub-directory (e.g. /Mail/pop.mail.yahoo.com/). To back up your mail messages, save the files without extension, for example INBOX. To back up filters too, save the rules.dat file. The *.msf files are index files that will be automatically regenerated if removed. Save the entire Mail directory if you are uncertain what to save.


News settings and messages are stored in the News sub-directory (e.g. /News/news.mozilla.org/). Your subscribed groups are stored in the *.rc file (e.g. news.mozilla.org.rc). The complete news server groupslist is stored in hostinfo.dat (e.g. /News/news.mozilla.org/hostinfo.dat). *.msf files store message summaries. To back up news, save the *.rc, *.dat, and *.msf files.

Address book

In your profile directory, save abook.mab (personal address book) and history.mab (collected addresses). If you have more than one address book, save all *.mab files.


Save the bookmarks.html file.

Saved password data

Username and password data is stored in 12345678.s (the number part is random). Save the file.

Saved form data

Saved form data is stored in 12345678.w (the number part is random). Save the file.

Junk filters

Save the training.dat file which stores information for the new smart filtering system.


Save the cookies.txt file.

User preferences

The main Mozilla configuration file is prefs.js. Save this file.

Customization files

Save user.js, chrome/userContent.css, and chrome/userChrome.css if you use them to customize Mozilla.

7.7. How do I restore my profile data from backup?

Normally, all you need to do is to restore with the backup copies of your profile files.

Exit the browser, and replace the relevant files in your profile directory with the backup copies. If after restart the profile data still appear to be “lost”, you may have a corrupted chrome cache file, in which case, exit your browser, delete the xul.mfl, xul.mfasl, or XUL FastLoad File file in your profile directory, and restart Mozilla again.

7.8. How do I rescue my data from a corrupted profile?

Item moved. See troubleshooting guide:

7.9. How do I transport my profile to a different machine?

Most of Mozilla profile files are in the same formats on all platforms, so it is possible to transport a profile across two different operating systems. To move a profile to a different machine:

  1. First, follow the instructions in 7.6 “How do I back up my profile data?” to make a copy of your profile data.
  2. Copy your profile files to the target machine. The profile location must be complete (BASE, NAME, and SALT). If possible, keep the profile locations the same between the old machine and target machine. If they are different, you will need to edit the profile configuration file manually.
  3. In the target machine, open the Profile Manager.
  4. Choose Create Profile, and then choose Next.
  5. Enter a profile name.
  6. Choose the Choose Folder button and navigate to the target profile location (BASE+NAME, excluding SALT).
  7. Choose Finish.

Hint to system administrators: if you want to copy the same profile as the default to many systems with CLEAN Mozilla installations, you can skip all these steps simply by copying all contents of the profile directory, including Registry.dat.

The opening screen of the Profile Manager reappears, with the new profile listed and highlighted. If the profile locations (BASE+NAME+SALT) are exactly the same between the old and target machines, you can start up your browser with the new profile by choosing Start Mozilla. If not, you will need to edit the profile configuration file:

Editing configuration file

  1. Exit the Profile Manager.
  2. In your profile directory, locate the prefs.js file and open it with a text editor such as Notepad or SimpleText. The configuration file is a list of entries like:

    user_pref("<setting>", <value>);
  3. Locate the entries for browser.cache.disk.parent_directory, mail.directory, mail.root.imap, mail.root.nntp, mail.root.none, mail.root.pop3, mail.newsrc_root, and news.directory (you may not have all of them). Delete these lines.

  4. Save the file and open Mozilla with the new profile.

  5. Open Messenger (you will find that none of your backup messages are imported yet.) In Messenger, open the Edit menu and choose “Mail & Newsgroups Account Settings...”

  6. In the Accounts pane on the left, navigate to the Local Folders account. On the right pane, change Local Directory to reflect the new profile directory.

  7. In the Accounts pane, navigate to each mail account. Navigate to Server Settings and change Local Directory to reflect the new profile directory.

  8. If you have newsgroup subscription(s), navigate to “Server Settings” for each news account. Change “newsrc file” and “Local Directory” to reflect the new profile directory.

  9. Choose OK.

  10. Exit Mozilla and then restart it. All messages should now be imported.

7.10. Can I share a profile with my copy of Netscape 7, or with an earlier version of Mozilla?

Do not share a profile with Netscape 6 or 7. Sharing profiles between different versions of Mozilla can lead to profile corruption

Note even if you uninstall a previous copy of Mozilla or Netscape, the old profile will still be there until you remove its folder. Be sure to create a fresh profile when you install a new version of Mozilla.

7.11. Does Mozilla support roaming profiles?

Mozilla does not yet support roaming profiles. A roaming profiles function is under development.

7.12. How do I protect data of my profile?

Currently Mozilla does not encrypt profile data, so you should use your system’s own security facilities to restrict access to your computer account.

7.13. How do I force Mozilla to open with a specific profile?

On Windows, Linux, and Unix systems, you can open open Mozilla with a specific profile using the following command line:

mozilla.exe -p <profile_name>

where <profile_name> is the name of the profile as appeared in the Profile Manager.

To open Mozilla in Quick Launch mode with a specific profile, the command line is:

mozilla.exe -turbo -p <profile_name>