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Firefox v86.0 reverts back to previous version.

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  • Last reply by FredMcD

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What is causing the browser to revert back to previous version? The previous version was 85.02. I have uninstalled Firefox and reinstalled v86.0. Eventually, the browser reverts back to the previous version. When I tried to open the browser, the following message appears:

You've launched an older version of Firefox Using an older version of Firefox can corrupt bookmarks and browsing history already saved to an existing Firefox profile. To protect your information, create a new profile for the installation of Firefox.

                                                                               Exit              Create New Profile
What is causing the browser to revert back to previous version? The previous version was 85.02. I have uninstalled Firefox and reinstalled v86.0. Eventually, the browser reverts back to the previous version. When I tried to open the browser, the following message appears: You've launched an older version of Firefox Using an older version of Firefox can corrupt bookmarks and browsing history already saved to an existing Firefox profile. To protect your information, create a new profile for the installation of Firefox. Exit Create New Profile

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Macs: Make sure you install Firefox properly and that you do not run Firefox from within the DMG (Disk Images) file. https://support.mozilla.org/en-US/kb/how-download-and-install-firefox-mac

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I'm not having the issue on the Mac. We have Windows 10 Pro computers and they all have v85.02 installed. The v86.0 update installs then reverts back to v85.02.

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Do you still have v85.0.2 on your system? Remove it.


Let’s do a full clean re-install;

Note: Firefox comes in three or more folders on all computers. They are;

Maintenance: (Programs Folder) <Windows Only> Firefox itself: (Programs Folder) And two folders in the profile of each user on the computer for each Firefox profile for that user.

If you remove the Firefox folder, the user profiles would not be affected.


Download Firefox For All languages And Systems {web link}

Firefox ESR; Extended Support Release {web link}

Beta, Developer, Nightly versions https://www.mozilla.org/en-US/firefox/channel/desktop/

Install Older Version Of Firefox {web link}


Save the file. Then Close Firefox.

Using your file browser, open the Programs Folder on your computer.

Windows: C:\Program Files C:\Program Files (x86) Note: Check Both Folders

Mac: Open the "Applications" folder. https://support.mozilla.org/en-US/kb/how-download-and-install-firefox-mac

Linux: Check your user manual. If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it. See Install Firefox on Linux; https://support.mozilla.org/en-US/kb/install-firefox-linux

If you downloaded and installed the binary package from the Firefox download page, simply remove the folder Firefox in your home directory. http://www.mozilla.org/firefox#desktop ++++++++++++++++++++++++++++ Look for, and remove any Mozilla or Firefox program folders. Do not remove the Mozilla Thunderbird folder if there is one.

Do Not remove any profile folders.

After rebooting the computer, run a registry scanner if you have one. Then run the installer. +++++++++++++++++++++++++++ If there is a problem, start your Computer in safe mode and try again.

How to Start all Computers in Safe Mode; {web link} Free Online Encyclopedia