WSUS Client Logs
Windows 10 no longer creates a "WindowsUpdate.log" file in %WINDIR% like it used to.
It creates ETW (Event Tracing for Windows) traces which aren't viewable in a text editor.
The solution is to run the Get-WindowsUpdateLog command from PowerShell.
This creates a WindowsUpdate.log and, by default, places it on the Desktop.
This can then be opened in Notepad.