Windows update Error Code: 66A
Getting error code 66A – Windows update encountered an unknown error. Security Update for .NET Framework 4 on Windows XP, Windows Server 2003, Windows Vista, Windows 7, Windows Server 2008, Windows Server 2008 R2 for x64-based Systems.
Solution:
Go to the control panel -click uninstall programs, search for: “Microsoft .NET Framework 4 Client Profile” – Click on it and choose repair file.
Install the Windows update file after that – and it should work!