Firefox is known to have this issue for a long time and across all browser versions. The message means that it found Firefox already running and is refusing to open it a second time. But, if it is already running, shouldn’t you be able to open it? To understand this, let’s investigate why the message pops up.
Why Do I Get This Message?
This means that a different instance of firefox is running in the background. But you may also get this message if firefox crashes while in the middle of something. It is also possible that Firefox updated and some changes didn’t take place. If this happens then firefox isn’t going to shut down by itself like it normally does. There are a couple of tasks that firefox does when exiting. Firefox may freeze due to application bugs and become unable to complete those tasks. Due to this, the system may falsely detect a different firefox running in the background. To understand how we can fix this issue, first, we need to understand what a Firefox Profile is.
What is Firefox Profile?
Firefox Profile stores all the changes that you stored in Firefox. It is a folder in your local storage disk separate from the main Firefox program data. This is particularly helpful when anything goes wrong in your Firefox. You can reinstall the application without losing any of your settings. For consistency reasons, the browser locks a profile folder when it starts up. If a profile is already locked, it means that the browser application has created a lock file. This lets the system know that the application is using that profile to run. As mentioned above, it’s going to remove that lock file when it shuts itself down. If it failed to do so, the error message appears the next time you open the browser.
Firefox Not Responding, Firefox Is Already Running but Is Not Responding(Fixes)
Kill Off the Running Process
For Windows
For Linux/macOS
Remove Lock File on Profile
For Windows
For Linux/macOS
Run Under Safe Mode
For Windows
For Linux/macOS
Create a New Profile
For Windows
For Linux/macOS
Check Folder Access Rights
For Windows
For Linux/macOS
Reinstall Firefox
For Windows
For Ubuntu/Ubuntu-based/Debian-based
For CentOS/Fedora/Redhat-based
For macOS
Close Firefox Button on the Error Message Doesn’t Work?
If the close Firefox button does not work, you may need to end up force-killing it. Firefox provides an option to force quit the application in case of emergency cases. First, try the following methods to quit firefox. One thing to note here is that you should not force quit unless absolutely necessary. Force quitting multiple times can create duplicate session profiles which will give you trouble when trying to reopen it. If you cannot open firefox after closing it, follow the steps above to fix the issue.
How Do I Run Two Firefox Profiles at the Same Time?
You can run two firefox profiles at the same time using Firefox Profile Manager. To open firefox profile manager before running firefox, try the following. In Windows,
Open Powershell.Assuming default location, Type & ‘C:\Program Files\Mozilla Firefox\firefox.exe’ -ProfileManager press Enter.
In Linux and macOS,
Open Terminal.Type Firefox -ProfileManager and press Enter.
Continue below for all platforms.
If you see just one profile, you need to create a new one. Refer to the create a new profile section above.Once created, click on Start Firefox.Repeat the above step to open the profile manager a second time.Select a different profile and click on Start Firefox.
Does Running Multiple Profiles on Firefox Cause Firefox Not Responding?
Running multiple profiles is a feature provided by firefox. For a majority of users, multiple profiles work just as fine as using a single profile. That being said, an average internet user may not know how to set up multiple profiles. The steps may be confusing to setup and access. Thus a less experienced user is more likely to get stuck due to profile locks, deleted default profiles and so on. Thus you are likely to run into the firefox not responding issues if you haven’t set up profiles properly. Multiple profiles are generally used by developers and more advanced users. If you are comfortable using multiple profiles and can troubleshoot when needed, it actually serves you a lot. Personal information such as bookmarks and passwords are stored in profiles. If you use a shared PC, you may want to take advantage of this feature. But make sure other users are also comfortable using it.
