Profile in use

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This article explains how to regain access to a locked or unavailable profile. This occurs if

  • You receive a message that the selected profile is already "in use" while using the Profile Manager
  • You start the application and it won't run, but it doesn't display any error messages.
  • You see an error that your SeaMonkey or Firefox "profile cannot be loaded. It may be missing or inaccessible" [1]
  • A "Close Firefox", "Close Thunderbird", or (starting in SeaMonkey 2) "Close SeaMonkey" dialog box appears with one of these messages (using Firefox as an example) [2]:
    • (On Mac OS) A copy of Firefox is already open. Only one copy of Firefox can be open at a time." [3]
    • (On Mac OS) A copy of Firefox is already open. The running copy of Firefox will quit in order to open this one.
    • Firefox is already running, but is not responding. To open a new window, you must first close the existing Firefox process, or restart your system. (shown below):
    • Firefox is already running, but is not responding. The old Firefox process must be closed to open a new window.

Note: Starting in Firefox 34 on Windows (Vista and above), the "Firefox is already running" dialog includes a "Close Firefox" button (shown here) that, when clicked, will dismiss the dialog, end the Firefox process(es) and, after a few seconds, will automatically restart Firefox. [4].

Common causes

The most common cause of this error is that your Mozilla application did not shut down properly. It might still be running in the background (even though it's not visible) or it might have closed abnormally, without deleting the lock file. To avoid conflicts, Mozilla applications such as Firefox, Thunderbird, and Mozilla Suite/SeaMonkey are designed to allow only one copy of the application to access a profile at the same time. This is done by checking for the existence of a lock file when it starts. If the lock file already exists, the application exits with an error message. Otherwise, it creates a lock file in the profile and deletes it at exit. Normally this is completely transparent to the user; however, in the case of an abnormal shutdown, the application might not delete the lock file, preventing you from using the profile. Other causes include the following:

  • This error can occur because of a delayed shutdown, if you try to reopen it too soon after it was last closed. [5] [6]
  • Another possible cause is that your Mozilla application cannot find the profile folder because it is not in the expected location (see below).
  • This error will occur if you moved the profile to an external drive and forgot to turn it on. You might also run into it if the profile is on a file share and you didn't mount it/redirect the drive to it.
  • 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 another instance running that uses the default profile and that was started with the -no-remote argument (or you have the environment variable MOZ_NO_REMOTE=1 set). [7] [8] You should never use -no-remote to start the "default" profile. See Opening a new instance of your Mozilla application with another profile for more information.

Note: Entering an incorrect -profile <path> command line argument used to produce this error and was commonly caused by entering -Profile Manager by mistake (instead of the correct -ProfileManager argument) when trying to start the Profile Manager. [9] [10] Currently, due to the fix for bug 531532, instead of producing an error a new profile is created at <path> and launched.


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 system error-checking tool (e.g., Chkdsk in Windows 2000/XP/Vista/7 or ScanDisk in Windows 98/ME). [11].

Check the profile folder name and location

If your Mozilla application cannot find the profile folder it will typically report that the profile is in use or, in Firefox, Thunderbird, and SeaMonkey 2, that the application "is already running, but is not responding" or that your "profile cannot be loaded. It may be missing or inaccessible". 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).

If possible, you should restore the profile folder to its original name and location, so that your Mozilla application can find it. Alternately, you can edit the "profiles.ini" file to show the changed location (see below) . Another solution is use the Profile Manager to create a new profile that points to the new folder location, by using the "Choose Folder" option during the profile creation process. See Moving your profile folder for more information.

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 the profiles.ini file

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 can 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:


If you can't spot an error in that file try running the Mozilla application with a specific profile using command line arguments. This bypasses the profile manager and profiles.ini. If you succeed then you know that the problem is with profiles.ini, For example,

firefox.exe -profile "C:\Documents and Settings\<user>\Application Data\Mozilla\Firefox\Profiles\xxx.default'' 

That example is for XP. <user> is the Windows log-in user account name and "xxx" is a random string.

If that fails check that the location of each profile is correct and edit its location in the profiles.ini file if necessary. If that fails you probably need to use the Profile Manager to create a new version of that file (see below) but there are a couple other solutions you should consider first.

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.)

Initialize the connection to a file share

If you are running Windows and store the profile on a file share try accessing the file share beforehand using Windows Explorer. Some users have reported this prevents the problem.

Create a replacement

Mozilla applications are extremely picky about the contents of the profiles.ini file, they will not ignore any errors in it, even if they're for other profiles. If you can't fix the problem by editing the location backup the profiles.ini file, delete the original, and then follow the instructions in Move your profile folder - Thunderbird or Moving_your_profile_folder to create a new known good profiles.ini file and have the profile manager update it with the location of your profile. If that works you can "move the profile" again to tell it about other profiles.

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 transfer your data from the locked profile to the new profile.

See also

External links

Related bug reports