There's a change for Windows Update logging in Windows 10 Build 9926 that you should be aware of



From SuperSite for Windows:

If you're be looking for information about Windows Update processing in Windows 10, you should know about a change that is introduced with Build 9926. In the past, the WindowsUpdate.log file (location: %windir%\Windowsupdate.log) provided information about updates downloaded and installed, and whether update installations were successful or not, among other things.

If you open the WindowsUpdate.log file in Windows 10 Build 9926, you'll be met with a placeholder message

  Windows Update Logging Change in Windows 10 Build 9926