After W10 upgrade revert to W8.1 on UEFI machine

Assume a computer with the UEFI firmware interface.

Assume that during or after a user has upgraded a W8.1 machine to W10 things go horribly wrong - Black screen, Blue screen, No screen. The user now tries to Boot from a USB Emergency Boot Disk that they previously created using the W8.1 utility and then they try to restore W8.1 from a System Image Backup (the one in File History) that they previously created.

Will this be possible and will the Product Key in the UEFI firmware allow a reinstall of W8.1 after a W10 upgrade...?

T.

Alphanumeric, thanks for your reply. Your guess that "....somebody at Microsoft likely knows...." is just a little scary..

Under the UEFI specification and the requirement by Microsoft that users are able to restore their systems to a "factory state" has resulted in OEM manufacturers creating their own bespoke disk partioning layouts. For example, a typical disk layout at the time of leaving the manufacturer may look something like the following: -

1. Recovery partition #1 (usually quite small around 100MB)
2. EFI System partition (also quite small, around 250MB)
3. OEM partition (less than 1GB)
4. Recovery partition #2 (large, up to 50GB)
5. Windows OS partition - C: drive
6. Optional Data partition - typically E: drive

The above layout is representative and is not necessarily identical for all manufacturers.

After upgrading a W8.1 machine to W10, what changes (if any) will be made to this partition layout and what changes (if any) will be made to the contents of these partitions..?

For example, will the upgrade make changes only to the Windows OS partition..? And the other partitions, will they remain as is..? Assume 6 months after the W10 upgrade a user has a terminal problem with their system and they decide to revert to the "factory state", what do they get - a W8.1 system as it left the factory, or something else..?

It is going to be really tough for IT technicians if these questions are only answered when we have a crisis to resolve.

T.

alphanumeric said:

You can download install media from here, http://windows.microsoft.com/en-us/w...-refresh-media that will let you clean install Windows 8.1. That media will accept Windows 8.0 keys and Windows 8.1, and will read OEM embedded codes from your BIOS automatically. You don't even need to know what your OEM key is.

If the 8.1 computer came with 'Windows 8.1 with Bing' then I'm not sure the above would work?

alphanumeric said:

But who said anything about 8.1 with Bing? You can't download Enterprise or VL editions from there either.

True , but the Enterprise or VL folks should have an IT department who should support them.

8.1 with Bing is the one sold to the public - I saw the 'with Bing' versions advertised for several cheap computers and laptops (perhaps still are for all I know) and I bet most of the people who bought them wouldn't know whether it was 8.1 Core or 8.1 Bing which they'd got - it would just be '8.1' (if they even registered that much).

Of course as it seems 8.1 Bing upgrades to Windows 10 Home which it seems will be clean-installable later, then 8.1 with Bing now looks like a better option.

Alphanumeric and DavidY, thanks for your replies.

I support computers that run a number of flavours of both W7 and W8.1, including some with "with Bing". I have never given "with Bing" much thought as there does not seem to be any discernable difference between the "with Bing" or the "without Bing" flavours. Many very capable business desktop PC's run the "with Bing" OS and I am almost certain that (except for the default browser) that the code is identical to the core.

What I will need to understand before August is whether there will be any practical "hands-on" difference when upgrading a W8.1 and a W8.1 with Bing. Prior to starting this Thread I had not given that any thought - so the point raised by David is a valid one, something that I at least need to be aware of even if I don't quite grasp the implications.

Referring back to Post #4 by Alphanumeric. Personally I hate the "factory reinstall" idea and have never used it on my personal computers - I have always used a System Image, either using the Windows utility (the one available from File History) or a 3rd-party, such as Seagate Disk Wizard (Acronis). However, you can never persuade everyone to do this and I know that many users will do a factory reinstall every time Windows is feeling a little unwell - this is especially the case with users who use NAT or the Cloud for data storage.

After the W10 upgrade it is going to be interesting to see what happens the first time a user hits that little "Factory Refresh" button on the keyboard.....

T.

alphanumeric said:

One thing to keep in mind is 8.1 with Bing has its own set of keys and its own ISO. Core and Core SL will not accept With Bing keys.

Thanks for the reminder - that makes sense considering that the "with Bing" was a no charge option to the OEM.

The following is compliments of Softpedia.... not sure if Gabe has made it more clear or muddied the waters....

Microsoft has confirmed today, through the voice of Gabe Aul, head of the Windows Insider program, that clean installs will be possible for those who upgrade to Windows 10 for free from any of the supported Windows versions, but no other details have been provided.
He has mentioned that you will be able to clean install Windows 10 on that PC at any given time for as many times as you want, so probably, your product key for Windows 7 and Windows 8.1 can be used for re-activating Windows 10 automatically in case that happens.
“You will not need your 8.1 key, the same device will reactivate once it has been successfully upgraded to 10,” Aul has explained.

And Gabe didn't address the question of whether the user will be able to revert to W7/W8.1 with that key.

T.