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Can't uninstall Firefox

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I have Windows 7 Professional and Kaspersky Internet Security. I had Mozilla Firefox 49.0.1. I also had Mozilla Firefox 42.0 in my Programs and Features List. I recently switched to Kaspersky Total Security and it told me that it was updating my MF 42.0 to MF 49.0.1. I wondered why I still had 42.0 in Programs and Features. When I try to uninstall it, under Administrative Account, I get "You do not have sufficient access to uninstall MF 42.0. Please contact your sysadmin." Every few hours Kaspersky Total Security would tell me it was updating MF 42.0. This was making me nuts, so I tried disabling/uninstalling it with CCleaner. Didn't work. I tried Revo Uninstaller. Didn't work. Finally I said, "Screw it!" and tried to uninstall MF 49.0.1 from Programs and Features, thinking that if I uninstalled 49.0.1, 42.0 would go with it and I could get a fresh copy. I got "An error occurred while trying to uninstall MF 49.0.1 (x86 en-us) It may have already been uninstalled. Would you like to remove it from the Programs and Features List?" I clicked NO, and looked up how to uninstall MF 49.0.1 online using the Helper uninstaller. So that was gone, but it's still in the Programs and Features List. So is MF 42.0. MF 42.0 is still hanging around, and Kaspersky Total Security was trying to update it every few hours. Finally, I hit "Ignore" to keep Kaspersky from nagging me about the software "Update". But this is making me crazy! I had to reinstall MF 49.0.1 just so I could post this question: How do I get rid of this MF 42.0 file? How do I properly uninstall MF 49.0.1 so that they both disappear from my Programs and Features and don't leave little pieces of code lying around? Thanks for your time, and for any advice you can give me. I appreciate it.

All Replies (3)

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Hi, turn off Kaspersky Total Security or preferably, go into its settings and stop it checking for programs that aren't up to date - setting it to Ignore may not do it! Now try performing a Clean reinstall. This means you remove your Firefox program files and then reinstall Firefox. This process does not remove your Firefox profile data (such as bookmarks and passwords), since that information is stored in a different location.

To do a clean reinstall of Firefox, please follow these steps: Note: You might want to print these steps or view them in another browser.

  1. Download the latest Desktop version of Firefox from (or choose the download for your operating system and language from this page) and save the setup file to your computer.
  2. After the download finishes, close all Firefox windows (or open the Firefox menu New Fx Menu and click the close button Close 29).
  3. Delete the Firefox installation folder, which is located in one of these locations, by default:
    • Windows:
      • C:\Program Files\Mozilla Firefox
      • C:\Program Files (x86)\Mozilla Firefox
    • Mac: Delete Firefox from the Applications folder.
    • Linux: If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see Install Firefox on Linux. If you downloaded and installed the binary package from the Firefox download page, simply remove the folder firefox in your home directory.
  4. Now, go ahead and reinstall Firefox:
    1. Double-click the downloaded installation file and go through the steps of the installation wizard.
    2. Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.

More information about reinstalling Firefox can be found here.

WARNING: Do not use a third party uninstaller as part of this process. Doing so could permanently delete your Firefox profile data, including but not limited to, extensions, cache, cookies, bookmarks, personal settings and saved passwords. These cannot be easily recovered unless they have been backed up to an external device! See Back up and restore information in Firefox profiles.

Please report back to say if this helped you!

Thank you.

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Thank you for your reply. I turned off Kaspersky's Software Update Checker, then I deleted the FF installation folder at C:\ProgramFiles\Mozilla Firefox. I decided not to reinstall Firefox for now, just to see what would happen. After uninstalling Firefox, I turned on Kaspersky's Software Updater and removed Mozilla Firefox from the Exclusions List. (Hey, what's the harm? It's no longer on my computer, right?) I went to Control Panel/Programs and Features, and both Mozilla Firefox 49.0.1 and Mozilla Firefox 42.0 are in the Programs and Features List. I don't have sufficient access to remove 42.0, even as an administrator. 49.0.1 says it "may" have been removed from my system. Kaspersky Total Security has once again advised me that Mozilla Firefox 42.0 needs updating to 49.0.1, so I added it back to the Exclusions List. I'm stumped as to what to do next. Any advice is appreciated. Thank you.

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After deleting the Mozilla Firefox installation folder, the Software Updater continues to inform me that Mozilla Firefox needs updating--this time to 49.0.2. I didn't reinstall Firefox after deleting the installation folder, and when the Software Updater came up to tell me that it had successfully updated Firefox 42.0 to 49.0.2, a couple of hours later it advised me that it was going to do so again. I set it to "ignore this update" and it hasn't nagged me since. My question is: How do I completely remove Mozilla Firefox from my system? I don't want to disable the Software Updater because it is useful-- it helped me do some updates on my Vista laptop that I had had a terrible time updating from the website. With the Software Updater, I hit "Update" and with one mouse click it was done for me. Is there a third-party uninstaller I can use to uninstall it that won't mess things up so that I can install it later if I want to? I don't care about saving profiles, bookmarks, etc. I can start over with those. I just want it gone for now. Thanks for your help.