Free Windows 10 'Custom install' option not available on a Windows 8.1 laptop any more!

[adamamerica]

I am trying to make my Lenovo Z710 Windows 8.1 laptop a dual boot laptop.
I did shrink the Cartion (with Windows 8.1) to 77 GB. This leaves a lot of unallocated space for a large partition for a clean install of Windows 10 on the 1 TB hard drive.

When upgrading ( a couple times) in the past 10 months to Windows 10 I saw the option 'Custom install'. Now I don't see it.
I only see the "Keep nothing" option. - This is only an in-place upgrade, i.e. Windows 8.1 is upgraded to Windows 10 (in the C;-partition).

I have the free Windows 10 ISO image which I downloaded today. I also used the free USB bootable Windows 10 which I created in May this year.

Here's some more information about my laptop.

Information
BIOS Version: ...
EC Version: ...

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Security
Secure Boot Enabled

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Boot Mode
USB Boot

UEFI enabled

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Any help would be appreciated,

Adam

 

[Colif]

You seem to be following the steps shown here: http://www.howtogeek.com/197647/how-to-dual-boot-windows-10-with-windows-7-or-8/

Are you booting off the Installer? It only offers custom if you boot from installer. You may need to remove secure boot to boot off USB

 

[adamamerica]

Hi,

You're right, booting off the Installer gives the 'Custom install' option.
I have installed free Windows 10 using my USB flash drive.
I needed to select my Lexar USB drive in the Boot Menu.
(The pre-windows environment system does not select it automatically.)

By the way, the secure boot was enabled .


Can I manually click on the Installer to boot off it???
Where can I read about a difference between
booting off the Installer vs. running the setup.exe.
Are there any other ways to invoke/run the Installer?
Any guide or threads on this site?



So far, when I was upgrading to Windows 10 (several times since August 2015),
I was double clicking on the setup.exe in the windows 10 ISO file on the desktop, on the USB drive or on the DVD.


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There's one glitch: I am NOT getting the dual boot selection screen

I did set Windows 10 as a default system, so my Lenovo Z710 boots directly into windows 10,
without giving me the above selection screen.

I also set the timer to 5 seconds. This causes that I cannot type in my password for 5 seconds.
(Simply, the password field is locked for 5 secs.)

However, once logged in I can go to the Advanced Options and click on the following option:
'Choose the other system'
and boot into the Windows 8.1 system.


Thank You very much,

Adam

 

[Colif]

I think its tied into fact win 10 would have created its own partition to boot from and not used same file as Win 8.1

I think you need to read this, it should fix this: http://pcsupport.about.com/od/fixtheproblem/ht/rebuild-bcd-store-windows.htm

http://www.thewindowsclub.com/dual-boot-repair-tool-bcd

 

[adamamerica]

Thank You very much. I will study those two articles carefully.

Yesterday, I was on Windows 10 and could miraculously switch to Windows 8.1.
Today I am stuck with Windows 8.1 and there's no way to switch to Windows 10.
No magical Advanced Options, etc.

Cheers,

Adam