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UEFI + Secure Boot not logging into W10 (dual-boot)

doriandiaconu

Honorable
Nov 2, 2013
39
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10,530
Hei,

So I'm the guy who tried to move from Legacy to UEFI some days ago. I managed to move both Ubuntu and W10 to UEFI.

More info on both of the situations here:

https://www.tenforums.com/drivers-hardware/72202-cant-boot-into-uefi-mode-lenovo-z50-70-a.html

http://askubuntu.com/questions/859952/queston-about-grub2-uefi

It seems that when I enable Secure Boot I keep getting these errors (It works if Secure Boot is not enabled, also Ubuntu boots just fine):

113546d1481728736t-uefi-secure-boot-not-logging-into-w10-dual-boot-dsc_0004.jpg

113545d1481728736t-uefi-secure-boot-not-logging-into-w10-dual-boot-dsc_0003.jpg

113544d1481728736t-uefi-secure-boot-not-logging-into-w10-dual-boot-dsc_0002.jpg
 
I'm surprised Linux works fine and Windows is struggling - as that's the exact opposite of the intend of SecureBoot, although Ubuntu did get signed by MS, so it *shouldn't* have issues.

When you installed Windows 10..... did you select the "UEFI" option for your USB?
If you installed in legacy by mistake, opposed to UEFI, then you'll have issues once enabling SecureBoot (as UEFI would be enabled)

I'm not 100% sure on this aspect, but Windows may 'seek;' to configuration that was in place when Windows was installed. You likely had to enable UEFI+CSM with Secure Boot disabled, so enabling SecureBoot and removing CSM might be the issue too.

It's covered off here: http://www.tomshardware.com/forum/id-2770945/install-windows-disabling-secureboot-fastboot.html

How to boot to your USB without CSM and with SecureBoot enabled - requires downloading the ISO and creating bootable media via Rufus.
 


It was indeed installed in Legacy mode. But I converted the MBR partition to GPT, so I think it should be working fine.
 
Converting after it was installed? I've never done it, but I know it can be done with Diskpart etc - but that doesn't 'fully' cover to GPT AFAIK (just an MBR/GPT type hybrid). That's lilkely where your issues lie. Windows (specifically the boot mgr) will not 'see' it correctly as GPT, as far as I know.

It is prompting you to rebuild the boot manager though (using 'repair'), so you might be able to rebuild it for GPT to allow for true UEFI and SecureBoot support... Otherwise, your only option is to reinstall in UEFI mode, but I don't know how that will impact your dual-boot ability.
 
Correct. It's probably worth downloading the ISO and creating the USB via Rufus (as detailed in the thread I linked) to allow you to boot from it with SecureBoot enabled (otherwise, you have do disable SB to boot from a USB, which defeats the purpose).
 
Looks like the startup repair did work, as far as being able to boot to Windows with secure boot enabled?

The failed results are likely a result of the MBR to GPT conversion you did earlier, there's really no way around that without truly formatting & installing in GPT