Error in updating windows
However, not everyone is having a smooth upgrade experience.
Microsoft has been proactively working to ensure Windows 10 is bug-free.
Windows Update is sometimes underestimated as a cornerstone of your system’s integrity and security.
Microsoft regularly delivers security patches, hotfixes, and software updates through Windows Update, and so if this service stops running or is turned off, then Windows can become vulnerable to bugs and security holes.
Before updating Firefox, try closing or disabling such programs; for example, Spybot Tea Timer and Logitech Quick Cam software have been known to interfere with Firefox updates.
This article provides the information on "Windows 10 Update Error C1900101-40017".