Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

Browser failure/slowdown after May 2020 Windows Update

more options

After installing the May 2020 Windows Updates Firefox and other browsers either would not open or opened after a long delay then failed to connect (works when starting Windows in Safe Mode as currently). I have uninstalled the 2 Windows Updates but cannot uninstall the security update of the same date - still have the problem.

I have Windows 10 and the latest Firefox (70.1).

I've run diagnostics, malware and antivirus scans, cleared the cache but still Firefox won't work.

I'm not tech savvy but am sure this is to do with the Windows Update - nothing online about resolving this. Would welcome help as am desperate.

All Replies (2)

more options

Have you tried reinstalling Firefox? It's not completely unheard of for a Windows update to damage your Firefox installation.

Certain Firefox problems can be solved by 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: (Note: Check both folders.)
      • 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.


more options

Thank you. Currently it's now working and hopefully will continue to do so - but sometimes it works for a while then the problem recurs. I appreciate your help.


Ask a question

You must log in to your account to reply to posts. Please start a new question, if you do not have an account yet.