Before Windows 7, 8 or 8.1 workstations accept Windows 10 upgrades from your internal WSUS server, some modifications have to be done.
- Add MIME type “.esd” to your WSUS machine’s IIS Manager. Otherwise, the upgrade images cannot be downloaded.
- Add registry DWORD “AllowOSUpgrade” = 1 under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\OSUpgrade
- You can deploy the key e.g. via GPO.
- Update WSUS to the latest version and choose to download classification “Windows Upgrades”, product “Windows 10” and after synchronizing, enable the Windows 10 upgrades of your choice.
Otherwise, you will see errors in WindowsUpdate.log like 0x80240020.