A bad news for you Firefox users who are still sticking with Windows 7, because starting from Firefox 100, Windows 7 SP1 users must first install the KB4474419 update before updating Firefox, otherwise the Firefox installation may fail.
Why is this KB4474419 update needed?, well quoted from the Firefox page, this is because Mozilla has signed Firefox in the Windows Installer with SHA-256 compared to the older SHA-1.
So with that, users of Windows 7 SP1 and Windows Server 2008 R2 SP1, and Windows Server 2008 SP2 must install update KB4474419 to update SHA2-code signing support.
“Beginning in this release, the Firefox installer for Windows is signed with an SHA-256 digest, rather than SHA-1. Update KB4474419 is required for successful installation on a computer running the Microsoft Windows 7 Operating system” Mozilla notes.
Now for you Windows 7 users, don't worry too much, you can download the KB4474419 update manually via the Windows Update page in Control Panel, or you can download the update manually from the following page.
What do you think? are you still using Firefox on Windows 7? comment below guys...!!