Have spoken to Microsoft, installing Windows10TP is a "Wrong Path" to getting Windows 10. The only option is to completely reinstall Windows 8.1 then follow the usual upgrade path. Otherwise, you must purchase Windows 10 to receive a valid product key. In other words, if you installed TP, you must reinstall the previous OS then follow the standard upgrade path.
Repeating the same answer for Windows 10 circumvents WSUS, which I had given on Server Fault here as well since the OP is making the same mistake.
The solution is very simple, ensure that your copy of Windows 10 does not have any of the following value names listed under HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate
, if you are running Windows 10 OS - impact version: 1511 & 1607.
DeferFeatureUpdates
DeferFeatureUpdatesPeriodInDays
DeferQualityUpdates
DeferQualityUpdatesPeriodInDays
PauseFeatureUpdatesStartTime
PauseQualityUpdatesStartTime
ExcludeWUDriversInQualityUpdate
Quoting further from the same article "Why WSUS and SCCM managed clients are reaching out to Microsoft Online":
What just happened here? Aren’t these update or upgrade deferral policies?
Not in a managed environment. These policies are meant for Windows
Update for Business (WUfB).
Windows Update for Business aka WUfB enables information technology
administrators to keep the Windows 10 devices in their organization
always up to date with the latest security defenses and Windows
features by directly connecting these systems to Windows Update
service.
We also recommend that you do not use these new settings with WSUS/SCCM.
If you are already using an on-prem solution to manage Windows
updates/upgrades, using the new WUfB settings will enable your clients
to also reach out to Microsoft Update online to fetch update bypassing
your WSUS/SCCM end-point.
To manage updates, you have two solutions:
- Use WSUS (or SCCM) and manage how and when you want to deploy updates and upgrades to Windows 10 computers in your environment (in
your intranet).
- Use the new WUfB settings to manage how and when you want to deploy updates and upgrades to Windows 10 computers in your environment
directly connecting to Windows Update.
— "Why WSUS and SCCM managed clients are reaching out to Microsoft Online" : This post was authored by Shadab Rasheed, Technical Advisor, Windows Devices & Deployment (9 January 2017), Microsoft Windows Server Team .
NOTE: Be advised that the mentioned Microsoft article's list of Registry value names has typos.
Best Answer
The issue for me was related to having used CCleaner and/or Disk Cleanup Manager (Cleanmgr.exe) to remove leftovers of previous Windows 8.1 installation. This had removed the files but not properly removed registry traces of the previous installation that were still available to Windows Update (and in fact "Settings -> Update & security -> Recovery -> Go back to Windows 8.1" function was still available, even if non-functioning). In this condition, the 31 days upgrade protection mechanism was probably broken. This might be a bug in Windows Update actually.
The following registry file removed for me the traces of Windows 8.1 previous installation (also hiding the "Recovery -> Go back to Windows 8.1") and enabling the 1511 update. Be prepared to a very long update process (>4 hours for some users). For me, the 1511 update stalled at "Preparing to install updates 32%" for at least 2 hours with OS installed on a SSD storage. For your security, backup before applying the registry edit.
A similar advice to resolve a different kind of problem was given in this post in a user comment (hutsy).