You may receive this error when trying to install DotNet3.5 (.net) on Windows 10 and you are using a WSUS server. This error may occur of the .net installer is not approved in WSUS.
As a temporary workaround, change the registry key “UseWUServer” to 0. It is located at:
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU
After the registry change, restart the Windows Update service. You should be able to install .net at this time. Once done you should change this key back to its original value (or wait and allow Group Policy to do it for you.)
