Firefox does not start - claims that it is already open

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• After that restart of firefox does not start. is running in the Task Manager, but won't pop up. Reset safe mode and uninstall/reinstall won't help. OK so no reset.

  Win7 Pro. has worked ok firefox. but lately with 25 and 26 now, firefox does not start. I see that firefox is running in the Task Manager. but it will not just appear.
  If I still download and install it, it runs, but every time I restarted the system, it just does not work yet.
  Reset try:, safe mode, uninstall & reinstall, new/clean profile none of these work.

  
  

• Firefox does not start because he says that it's another instance that runs in the background, but I checked and it is not a!

  Firefox does not start because he says that it's another instance that runs in the background, but I checked and it is not a! I have Linux Fedora 15 and I'm not the root. I spoke to the Manager and he said I should delete a file in the folder where firefox is installed and which can solve the problem. Can you help me?

  Thanks, Marius
  

  Upgrade your browser Firefox 8 and check

  • getfirefox.com

• Firefox does not start "XPCOM" message pop up, my user and passwords! ??

  My window 7 was not starting up properly so I did a system restore and now firefox does not start a message appears indicating "XPCOM" and I googled and all is said to reinstall Firefox. I don't usually to reinstall immediately because I need my passwords and username back. I can't find a solution on the forums, or if there is I have not found or I simply did not understand the solution itself. Please get back to me as soon as possible

  Thank you!

  Is a restoration of the system to a cancellation of the recent updates or something more radical?

  You can do the following type of reinstall without touching your settings files. Important: uninstall NO Firefox first. That is not necessary.

  Clean reinstall it

  (1) download a fresh Installer for Firefox 36 of https://www.mozilla.org/firefox/all/ in an ideal location. (Scroll down your preferred language).

  (2) the release of Firefox.

  (3) to rename the program folder

  (Windows 64-bit folder names)

  C:\Program Files (x86)\Mozilla Firefox
  

  TO

  C:\Program Files (x86)\OldFirefox
  

  (Windows 32-bit folder names)

  C:\Program Files\Mozilla Firefox
  

  TO

  C:\Program Files\OldFirefox
  

  (4) run the installer you downloaded in the #1. It should automatically connect to your existing settings.

  When you start Firefox, you may need to use the Profile Manager to return to your regular profile. Ignore: copy/paste glitch.

  Any improvement?

  Note: Some plugins can only exist in this OldFirefox file. If it is missing something essential, present in these files:

  • \OldFirefox\Plugins
  • \OldFirefox\browser\plugins

• Firefox does not start (not safe mode), but uses the CPU

  I have the latest Firefox 25.0 (and the last Flash 11.9.900.117) on Windows 7 and the following behavior is reproducible. It started not too long ago.

  At first when I launch Firefox, nothing appears no matter how often, I restart. I see in the list of the process firefox.exe to 25% of the CPU, 2 x FlashPlayerPlugin_11_9_900_117.exe (CPU 0%) and plugincontainer.exe. No matter how many times I killed all of them, would not restart Firefox.

  The following also not help in this situation:

  • Starting in normal safe mode: Firefox opens a window but immediately freezes and does not respond. The process list shows the same process even if I find the unexpected FlashPlayer.
  • Disable plugincontainer: same results (just without plugincontainer.exe)
  • Uninstall Flash: Same results (just without FlashPlayerPlugin)

  The following can start Firefox only once:

  • Starting in SafeMode but select "Reset Firefox": Firefox does not start right away, however. Nothing happens, and you have to kill the process. However the very next time you launch Firefox in the normal way, it works fine (but it shows FlashPlayerPlugin.exe in the list of unopened Windows process despite the tab). Unfortunately, after closing Firefox the process (Firefox, FlashPlayerPlugin) are not deleted. I kill and the problem with Firefox do not leave reappears.

  In case you use "clear history of Firefox closing:

  • do not delete Cookies

  Note that compensation "Preferences of Site" clears all exceptions for cookies, images, windows pop up, installation of software and passwords.

  Use "Firefox > output" (Windows: Firefox/file > quit;) Mac: Firefox > quit Firefox. Linux: Firefox/file > exit) to close Firefox if you are currently doing by clicking on the X close in the title bar of Firefox.

  Create a new profile manually (and not via the reset) as a test to see if your profile is the source of the problems.

  See "create a profile":

  • https://support.Mozilla.org/KB/Profile-Manager-create-and-remove-Firefox-profiles
  • http://KB.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

  If the new profile works then you can transfer files from a profile in the new profile, but be careful not to copy files corrupted to avoid transporting on the problem.

  • http://KB.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

• I get this error message and Firefox does not start... EXC in ev handl: error: error definition property on NPObject!

  Firefox does not start and this message keeps coming back... I uninstalled and reinstalled... but nothing helped...

  EXC in ev handl: error: error definition property on NPObject!

  Disable the extension "McAfee Site Advisor" who has just updated 3.4.0 that probably out of block of addons list.

  • 'Ctrl + Shift + A' > find McAfee Site Advisor and use 'Disable', and then restart Firefox.
  • Do a Google search without problem
  • It seems that if you re - enable new Site Advisor and restart Firefox you agree. At least you know where to look if you get the error again, or research on Google to slow down.

• Mozilla Firefox does not start

  My Firefox does not start. I've tried the upgrade, the problem still persists. The icon is there, but nothing happens when I press it.

  Hi Dick3974,
  Please reinstall Firefox for Android from Google game store and see if this problem persists.

  We look forward to your response.

• Firefox does not start after the computer restarts

  Install Firefox, works great. Restart the computer, Firefox does not start, or finally when it tries to start the script errors occur. If I reinstall Firefox after restart of a computer, it works fine, once again when the computer is stopped at the next startup it is, will not be able to use Firefox. Firefox does not start in Firefox Safe mode, does not start in windows safe mode. Do not add now, nothing has been added, just the Firefox installer played complete the system restore on the computer, same problem. Windows 7 Pro. Remove Firefox from windows control panel, restart your computer, install firefox, will take place. shut down the computer, put on the computer, firefox does not start, or crashes. I am exploring now Web interface.

  I reinstalled Firefox, so it will run in order to perform the steps below.

  Here is the answer which took care of the problem,

  http://KB.mozillazine.org/Browser_will_not_start_up#Problematic_plugin_prevents_browser_from_starting

  "Site Web TrueSuite Log On" plugin (AuthenTec), is the question.

• Firefox does not start. Error oxc0150004

  Firefox will not start. I uninstalled and reinstall.
  Nothing has changed. I have used Firefox for years. This first
  time, I have a problem.

  Hey Horrie.

  Have you tried to start Firefox in Mode safe? Key 'shift' startup of Firefox. If the accident is not in Mode without failure, you should read the extensions, themes and problems of hardware acceleration to resolve common troubleshooting Firefox problems.

  There are also a lot of useful things in the article Knowledge Base of Firefox does not start . If you have recently upgraded, you can check out this article as well.

  Hope this helps!

• 9.01 Firefox does not start, has a dialog box saying: it is still ongoing.

  Does anyone have ideas with the following Firefox Vista problem.

  9.01 Firefox does not start, has a dialog box saying: it is still ongoing.

  There is no instance of firefox in the Task Manager.
  I uninstalled firefox and reinstalled both of
  Desktop mode and course in vista.

  I have deleted all instances of firewall.

  I tried with firewall failure

  Still having the same problem

  Solved by uninstalling all the firefox - including my settings

• After that update of windows 64 bit system Firefox does not start

  I've updated to IE 10 and it should be updated to complete. My preference is Firefox, but it does not start and produces an error box telling me that Firefox could not start, it also sends you a report of failure.
  It happened in a previous windows update and to reolve that I go back to an earlier era. I don't want to do that this time, I want to use 10 IE and Firefox. If you are unable to solve this I have to use IE 10, it is so much faster now.

  Yes thanks - please start firefox in safe mode (by pressing the shift key, while it launches) and go to firefox > options > advanced > general & disable hardware acceleration.

  for some information about this, you can also look at bug #812683

• Firefox does not start, the Profile Manager is not available

  Firefox worked, then update it does not start. I tried all the fixes; However, the Profile Manager is not accessible or even present in the execution file. I unintalled and reinstalled several times, but I still can't get it to work. There is no Windows or Norton firewall block so I do not understand. What can I do? I want to use Firefox because it's the best browser; but now I'm forced to use Oscar. It's not terrible, but I prefer the features I've had with Firefox

  I had upgraded to the latest version; but the thought of demotion to the version which worked perfectly. In the end, I had to defrag, do a registry clean and optimization of performance of PC, but for the upgrade launched. So, I'm happy to say that I reply to this post with my Firefox browser. Thank you very much for your help. If all goes well, I won't have problems.
  DoubleD52

• Firefox does not start after the places.sqlite opening in Notepad

  Firefox does not load again. I tried to create a large folder of bookmarks, but I wanted them to hide so I tried to be clever and create a copy of my current places.sqlite who had no bookmarks added and moved elsewhere, then I added bookmarks and once that replace the current places.sqlite then I created a copy of this and put it elsewhere for more security and then I replaced it with the first places.sqlite I had copied. I had to go through that much trouble because for reasons, I was unable to delete the bookmarks by right-clicking and selecting delete. I had already tried to open places.sqlite in Notepad and since then is when it started to happen. I tried to reset the file extension type, or rather detached, but I can't figure out how. I also tried to remove completely any Mozilla partner, restarted my computer and then reinstall Mozilla, but it didn't work and I prefer not to try again or uninstall it because my computer has a very difficult time even boot Windows 10. He likes to get on the desktop and then never hang while I have to restart the computer continuously until it works.

  Can someone tell me what to do or where it is that I was wrong?

  Do a clean reinstall and delete the program folder before Firefox to (re) install a new copy of the current version of Firefox.

  • Download the installer of Firefox and save the file to the desktop
    https://www.Mozilla.org/en-us/Firefox/all/

  If possible to uninstall your current version of Firefox to clean the Windows registry and settings in the security software.

  • Do NOT remove the "personal data" when you uninstall your current version of Firefox, because this will remove all profile folders and you lose personal data such as bookmarks and passwords including data profiles created by other versions of Firefox.

  Delete the program folder Firefox before installing newly downloaded copy of the Firefox installer.

  • (32-bit Windows) "C:\Program Files\Mozilla Firefox\"
  • (Windows 64 bit) "C:\Program Files (x 86) \Mozilla.
  • It is important to remove the Firefox program folder to delete all the files and make sure that there is no problem with the files that were the remains after uninstallation.
  • http://KB.mozillazine.org/Uninstalling_Firefox

  Your bookmarks and other personal data are stored in the Firefox profile folder and will not be affected by a uninstall and (re) install, but do NOT delete personal data when you uninstall Firefox which removes all Firefox profile folders and you lose your data.

  If you keep the problems, and then create a new profile.

  • http://KB.mozillazine.org/Profile_folder_-_Firefox
  • http://KB.mozillazine.org/Profile_backup
  • http://KB.mozillazine.org/Standard_diagnostic_-_Firefox#Clean_reinstall

• When you start firefox, pop-up screen wishes to leave firefox to make changes on the hard disk on the computer. I must say yes, or firefox does not start. Next time.

  Is this a problem of firexfox, or something is wrong with my drive? I don't have this problem when you use IE or Opera, Firefox only. I have to let Firefox to make changes to my hard drive, or it does not start. Once I click on Yes, Firefox works. However, when I close Firefox and try to open it again, the thing is repeated with msg popup to change the hard drive...

  Make sure that Firefox is not set to run as administrator.

  Right click on the desktop Firefox shortcut and choose "Properties".

  Make sure that all items are disabled in the tab "Compatibility" in the Properties window.

  • Privilege level: "Run this program as Administrator" should not be selected
  • "Run this program in compatibility mode for:" must not be selected

  Also check the firefox.exe program properties in the program Firefox (C:\Program Files\Mozilla Firefox\) folder.

• Firefox does not start until the wifi is active

  I'm trying to use the latest firefox (v32) on Debian/testing/64-bit by using the 64-bit version of FF... This machine is a laptop and is used only with wifi. The wifi that is usually used is a Starbucks or McDonald's who require a click on a Web page before the connection is enabled... When I start FF to be able to select this check box, it does not start. a look at the ps - xua shows firefox as a zombie/missing process... How I work around this, is to use Google Chrome to shoot to the top of the Web page, click on the box, then almost immediately the instance FF I tried to launch rises... If I clicked on the icon of the FF once more, I get more window a FF... It seems that FF needs a pipe open to internet before it will start. I prefer FF on Chrome, but if I have to use Chrome to "Kick-start" FF, I might as well delete FF and just use Chrome... Any ideas?

  UH... This problem occurs on Linux... It IS not IE (thank God)... The proxy on FF and Chrome settings are identical, namely NO proxy configured...

  I've come up with a workaround.. Switched out the Linux drive with my pretty unused Windows 7 disk.. Where this problem with Firefox doesn't occur.. I'll check back in a few months with FF on Linux and see if one of the endless "updates" has magically fixed this problem.. Thank you for the help anyway..