Microsoft has been dealing with numerous issues since releasing Windows 10 update. It has already admitted officially the 0x80073701 error code which commonly appears when users download Windows 10 Version 1607 and try to install KB3206632 or KB3213986 updates for x64-based systems.
In case you are trying to install a cumulative update for the second time or more, it might be that the system already contains some of its components. That's why the error code 0x80073701 occurs
Remove the update that causes error code 0x80073701 manually
Go to Start menu and type Command Prompt
Right-click on that and select Run as administrator
Copy and paste the following command, press enter
wusa /uninstall /KB:3172605
There should be no errors after this
Manually download and install the update KB3081440
Navigate to the official Microsoft’s website and download the update KB3081440 from this link:
https://www.catalog.update.microsoft.com/Search.aspx?q=KB3081440