How to restore the system/boot drive letter in Windows 10?

#1
Hi

Please, advice How to restore the system/boot drive letter in Windows 10 and repair boot after dual boot setup with two Windows 10?

It causes boot errors and ChkDsk to run when switching to the other OS...
ChkDsk changed the system/boot drive letter:
Partition = C: (please, see bellow) initially was System Reserved Partition without assigned Letter.
Partition= G: initially was Partition C: with Windows 10 installed.

Windows Boot Manager
--------------------
identifier {9dea862c-5cdd-4e70-acc1-f32b344d4795}
device partition=C:
description Windows Boot Manager
locale en-US
inherit {7ea2e1ac-2e61-4728-aaa3-896d9d0a9f0e}
default {adebb11a-c5f6-11e5-acd1-84e0104f86c0}
resumeobject {adebb119-c5f6-11e5-acd1-84e0104f86c0}
displayorder {adebb11a-c5f6-11e5-acd1-84e0104f86c0}
toolsdisplayorder {b2721d73-1db4-4c62-bf78-c548a880142d}
timeout 30

Windows Boot Loader
-------------------
identifier {adebb11a-c5f6-11e5-acd1-84e0104f86c0}
device partition=G:
path \Windows\system32\winload.exe
description Windows 10
locale en-US
inherit {6efb52bf-1766-41db-a6b3-0ee5eff72bd7}
recoverysequence {adebb11b-c5f6-11e5-acd1-84e0104f86c0}
recoveryenabled Yes
allowedinmemorysettings 0x15000075
osdevice partition=G:
systemroot \Windows
resumeobject {adebb119-c5f6-11e5-acd1-84e0104f86c0}
nx OptIn
bootmenupolicy Standard


Startup Repair and Command Prompt are only two available options in Troubleshoot Advanced Option. Startup Repair wasn't successful Please, see more details here http://answers.microsoft.com/en-us/windows/forum/windows_10-update/how-to-repair-boot-after-dual-boot-setup-with-two/f1ea64c3-a13c-471a-b0fd-1be55454e861

Thank you very much.
 
Last edited:

mqudsi

Mostly Harmless
Staff member
#2
You can change the assignment of the system drive letter by editing HKLM\SYSTEM\MountDevices in the registry. Be careful when editing it though.
 
#3
Thank you very much maudsi,
Unfortunately, I cann't change the assignment of the system drive letter by editing HKLM\SYSTEM\MountDevices in the registry, because

Startup Repair and Command Prompt are only two available options in Troubleshoot Advanced Option. Startup Repair wasn't successful Please, see more details here http://answers.microsoft.com/en-us/windows/forum/windows_10-update/how-to-repair-boot-after-dual-boot-setup-with-two/f1ea64c3-a13c-471a-b0fd-1be55454e861

Thank you very much again.
 

mqudsi

Mostly Harmless
Staff member
#4
OK, I'm definitely misunderstanding. I didn't understand from your first post that you aren't able to boot.
There's no reason (yet) to believe that your drive letters are wrong - they're just random letters that each OS/platform/environment/installation might change at whim. The only thing that matters is if the OS itself thinks it's drive X:\ one day and drive Y:\ the next - that's when problems happen. @Terry60 is better than me at explaining this, we'll have to ask him to write it up in the wiki or something :smile:

Where are you getting the bcdedit output you posted? Is this from within the command prompt in startup repair/advanced repair?