Many users are reporting Windows Update becoming non-responsive after attempting to install KB3189866. KB3189866 is an important security update for Windows 10 Anniversary Update and includes additional improvements.
The best way to resolve this problem so far is to manually install KB3189866. You can do it one of two ways. Visit the Microsoft Update Catalog website using Internet Explorer:
Then download the appropriate copy of KB3189866 for your Windows 10 architecture (32 or 64 bit).
You can also download the appropriate architecture directly: