How to determine Windows 10 version when it is not running?

I have upgraded my Windows 8 to Windows 10 recently. After that, I bought a SSD drive for my notebook and removed the regular HDD drive from it and installed a fresh copy of Windows 10 (Home edition). The HDD was put in a external USB case, so I can access my old files and old Windows installation partition as well.

The problem is now I'm having some issues to activate my fresh installation of Windows. I'm not really sure that I should've installed Windows 10 Home or another version.

How can I determine which Windows version is in the old HDD, given that all files are still accessible, but the system itself is not running?

I could just swap the SSD and the HDD again and boot the old system, but it'll be better to find a "software" way of doing that. This answer addresses what I'm looking for, but for Windows XP. The proposed file doesn't exists in my old installation.

3 Answers

Where is my Windows OS Product information stored?

In a functional copy of windows, there is a couple of registry values which contain information about the Windows system.

This can be accessed through the Registry Editor by searching under:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion"

The registry 'hive', which is a subset of keys and values for the system, contains information such as CurrentVersion, ProductName and EditionID - these can be used to evaluate your type of Windows.

To check your version of Windows, locate the CurrentVersion value.

If you are running Windows 10, there are two new values that can be used to evaluate the OS version, CurrentMajorVersionNumber and CurrentMinorVersionNumber.

What if I want to check the version of an offline Windows?

• Plug the offline storage of Windows into a host machine (E.g. An old copy of Windows on a HDD).
• Locate the Registry Hives for the offline Windows. They are usually stored under C:\Windows\System32\config. You should notice the hives as regular file types named in ALL CAPS (E.g. SOFTWARE, DRIVERS, VSMIDK)
• Open the host system's Registry Editor by running regedit.exe.
• Select the HKEY_LOCAL_MACHINE folder. Click File/Load Hive. Load the SOFTWARE hive from you offline Windows folder.
  • Do not import the hive.
• Give the loaded hive a recognizable name so that you can locate it later.
• View/Modify the loaded hive/value is required. Click File/Unload Hive once you are done.

Alternatively, you can use a third-party registry editor on you host machine to view/modify the hives.

If you’re only concerned about the version, not edition or channel or whatever, you can simply look at \Windows\system32\ntoskrnl.exe:

You must then cross-reference that version number with known version numbers found on the Internet.

Boot using a password recovery tool using a usb stick. They all basically work the same way: First go into the BIOS and select usb boot. Using a different machine prepare a password recovery usb stick. These boot into some type of linux, edit the registry and either change or remove passwords. A little homework may be needed but choose one you are comfortable with. If all else fails, reinstall windows.