Profile in use

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This article deals with "already running, but is not responding" messages at application startup, as well as a "profile in use" message when selecting a user profile in the Profile Manager.

To avoid conflicts, Firefox, Thunderbird, and Mozilla Suite/SeaMonkey are designed to allow only one copy of a Mozilla application to access a profile at the same time. It does this by checking for the existence of a lock file when it starts. If the lock file already exists it exits with an error message. Otherwise it creates a lock file in the profile and deletes it when exits. Normally this is completely transparent to the user. However, if the Mozilla application exits abnormally it might not delete the lock file, preventing you from using that profile. This article will help you regain access to the "locked" profile.


Indications that your profile is locked

  • You launch the application, see the Profile Manager and receive a message that the selected profile is already "in use".
  • A "Close Firefox", "Close Thunderbird", or, starting in SeaMonkey 2, a "Close SeaMonkey" dialog box is displayed with a message that <Firefox, Thunderbird, or SeaMonkey> is already running, but is not responding. To open a new window, you must first close the existing <Firefox, Thunderbird, or SeaMonkey> process, or restart your system."


The most common cause is the application shut down abnormally. It might still be running in the background (even though its not visible), or it might have exited without deleting the lock file. You might also see this message in Firefox 3 because of a delayed shutdown, if you try to reopen it too soon after it was last closed. [1] [2]

Another possible cause is that your Mozilla application cannot find the profile folder because it is not in the expected location. [3]

You can also get this message if you try to open a link from an external program (e.g., double-click a link in an email or HTML file) and there is a Firefox instance running that uses the default profile and that was started with the -no-remote switch (or you have the environment variable MOZ_NO_REMOTE=1 set). [4] You should never use -no-remote to start the "default" profile. See Opening a new instance of Firefox with another profile for more about -no-remote.

How to unlock your profile

End processes

Go through your task or process list and stop each instance of the Mozilla application, or restart your computer. (If you need to do this on a recurring basis, read this for possible causes and solutions.)

Remove the profile lock file

The application may have shut down abnormally, leaving the lock in place. To fix this, open the profile folder and delete the file,
  • "parent.lock" (Windows),
  • "lock" and ".parentlock" (Linux), or
  • ".parentlock" (Mac OS X)

For Mac OS X: You need to use a free utility like Onyx or Maintain to turn on visibility for invisible files to show ".parentlock". This file contains no information, and deleting it will unlock the profile.

For Windows: If you attempt to delete the "parent.lock" file and receive the error, "Cannot delete parent: The file or directory is corrupted and unreadable", restart the computer and run the error-checking tool Chkdsk (Windows 2000, XP) or ScanDisk (Windows 98, ME) [5].

Check the profile folder name and location

If your Mozilla application cannot find the profile folder it will report that the profile is in use or, in Firefox, Thunderbird, and SeaMonkey 2, that the application "is already running, but is not responding". This can happen if you delete, rename or move the profile folder, if you run the application from removable media, or if the profile folder is stored on a network drive (bug 278860).

Firefox, Thunderbird, and SeaMonkey 2 look for the profile folder based on the information stored inside the profiles.ini file (see the linked article for details). You use a text editor such as Notepad to open the "profiles.ini" file to see what information it contains. Here is an example:



IsRelative=1 indicates a relative path in the expected profile location, as above.

IsRelative=0 indicates a custom (absolute) profile location, for example, someone might use this to put their profile on a thumb drive or removable disk:


Either edit the "profiles.ini" file to show the changed profile folder location or restore the profile folder to its original name and location.

Important: If you deleted your only profile folder, have no backup to restore and are now seeing the "already running" dialog box, delete or rename the profiles.ini file (or its parent Firefox, Thunderbird, or SeaMonkey folder) in the profile folder path. A new default profile will be created when you next start your Mozilla application.

Check access rights

This problem can also occur if you don't have the rights to edit the files in the profile (or create the lock file in the first place). Please note that this can happen if you try to use a profile from a filesystem mounted with read-only (e.g. a remote Windows share which doesn't have "allow network users to change my files" checked). This can be pretty tricky to diagnose because there is no lock file in the profile, yet the same message appears (profile in use). Incidentally, Linux users may have ~/.thunderbird and/or ~/.mozilla-thunderbird in their home directories if they have had more than one version of Thunderbird installed.

Check for other applications using the profile

SeaMonkey 1.x, Mozilla Suite, and Netscape 7 all use the same profile folder location and profile registry. If two or more of these programs are installed and you see a "profile in use" message, another of these programs may be using the profile. Try shutting down this program to unlock the profile. Additionally, you should create separate profiles for SeaMonkey 1.x, Mozilla Suite, and/or Netscape 7, as profile corruption can result if these programs share the same profile. (This problem does not occur with Firefox and Thunderbird, which do not share profiles with other applications in the same way that SeaMonkey 1.x, Mozilla Suite, and Netscape 7 do.)

Restoring data from a locked profile

If you are unable to unlock the profile using the above methods, use the Profile Manager to create a new profile and migrate your data from the locked profile to the new profile.

See also

External links

Related bug reports