1.    22 Jul 2017 #1
    Join Date : Oct 2014
    Posts : 19
    Windows 10 Pro

    Can't boot into main drive after installing Windows on another drive


    Hi guys,

    So I'm no longer able to boot into my main drive, but all my files and folders on that drive still look intact. I honestly don't know what went wrong or if there is any way to fix this other than reinstalling Windows. Tried startup repair on my Windows 10 installation USB, that failed. I'll explain every step I took.

    I should first mention I just built this PC and I bought an M.2 SSD to use as my main drive, but I also installed my SATA SSD from my old PC. After installing Windows 10 on my M.2 drive I was able to select which drive I wanted to boot into every time I started my PC. I didn't format that SATA SSD until just before when I went to install another copy of Windows on it. Here's what happened.

    I booted into my installation USB. My main drive (the M.2 SSD) was called drive 2 and my other drive (the SATA SSD) was called drive 0. I formatted then deleted the main partition of drive 0, then deleted all the smaller partitions of reserved space so the drive only had one volume of unallocated space. Then I selected that unallocated space and selected new, which recreated all the smaller partitions. I then selected the main partition of drive 0 and pressed next, which installed it on that drive. It installed successfully, but I first noticed something was odd when I didn't see the boot manager after I restarted my computer, it just automatically boots to the new copy of Windows. I noticed in my BIOS the boot order has the boot manager for my SATA SSD as the first and there's no boot manager for my M.2 SSD. Every time I try to boot into my M.2 SSD I just get a black screen with a flashing underscore symbol that moves back and forth between the top left and near center of the screen. I disconnected my SATA SSD so it could only boot to my main drive and the same thing happens.

    Anyone know what went wrong here? I never touched my main drive when I formatted, deleted and recreated partitions on my SATA SSD, and that one boots just fine. And are there any other steps to fix this before I just give up and reinstall Windows on that drive? Thank you.
    Last edited by apav; 22 Jul 2017 at 11:49.
      My ComputerSystem Spec
  2.    22 Jul 2017 #2
    Join Date : Jul 2015
    Posts : 9,381
    Windows 10 Pro

    When you installed Windows onto the M.2 SSD, you still had the SATA SSD installed. Windows setup found the EFI System Partition on the SATA SSD and put the boot files there instead of the M.2 SSD. That is why we recommend that you have only the drive connected that you want to install Windows on until the computer is successfully booting from it, then connect your other drives.

    Now, if you don't want to do a reinstall that way, you will have to make room on the M.2 SSD for an EFI System Partition formatted as FAT32 (250 - 500 MB in size) and manually create the boot files on it.

    Starting with a screenshot of disk management will help:
    Disk Management - How to Post a Screenshot of Windows 10 General Tips Tutorials
      My ComputerSystem Spec
  3.    22 Jul 2017 #3
    Join Date : Oct 2014
    Posts : 19
    Windows 10 Pro
    Thread Starter

    Quote Originally Posted by NavyLCDR View Post
    When you installed Windows onto the M.2 SSD, you still had the SATA SSD installed. Windows setup found the EFI System Partition on the SATA SSD and put the boot files there instead of the M.2 SSD. That is why we recommend that you have only the drive connected that you want to install Windows on until the computer is successfully booting from it, then connect your other drives.

    Now, if you don't want to do a reinstall that way, you will have to make room on the M.2 SSD for an EFI System Partition formatted as FAT32 (250 - 500 MB in size) and manually create the boot files on it.

    Starting with a screenshot of disk management will help:
    Disk Management - How to Post a Screenshot of Windows 10 General Tips Tutorials
    Thanks for letting me know! I didn't know it would do that. In the future I'll disconnect all other bootable drives except for the one I'm installing on. Now, would you recommend me reinstalling Windows or manually creating the EFI System Partition and boot files? If I manually create them will they be the same exact thing as the ones reinstalling Windows would create, and could I potentially run into any problems later with the manually created ones that I wouldn't if I just reinstall Windows?

    I'll be back home in a few hours, will post a screenshot then. Thanks again!
      My ComputerSystem Spec
  4.    22 Jul 2017 #4
    Join Date : Nov 2013
    Central Florida
    Posts : 346
    Win 7 Pro/32, Win 10 Pro/64/32

    Just to avoid collisions between several OS's, (I have six drives in my main PC, that could possibly boot the system)
    I make sure my main drive is connected to SATA port "0", on the motherboard, and that all other drives are either unplugged from the SATA ports or not powered up.

    Right now, I'm running on a hard drive sitting on the desk next to my tower, on which I've just installed Windows 10, Pro, 64.
    My main drive, a 128 SSD, mounted inside my tower, is unplugged. I like to keep peace in the family! lol

    Cheers Mate, and Good Luck,
    TechnoMage
      My ComputerSystem Spec
  5.    22 Jul 2017 #5
    Join Date : Oct 2014
    Posts : 19
    Windows 10 Pro
    Thread Starter

    Quote Originally Posted by TechnoMage View Post
    Just to avoid collisions between several OS's, (I have six drives in my main PC, that could possibly boot the system)
    I make sure my main drive is connected to SATA port "0", on the motherboard, and that all other drives are either unplugged from the SATA ports or not powered up.

    Right now, I'm running on a hard drive sitting on the desk next to my tower, on which I've just installed Windows 10, Pro, 64.
    My main drive, a 128 SSD, mounted inside my tower, is unplugged. I like to keep peace in the family! lol

    Cheers Mate, and Good Luck,
    TechnoMage
    Thanks for the tip TechnoMage! I'd definitely like to do that, problem is my M.2 SSD is underneath a cover that gets screwed into my motherboard, which is underneath my graphics card. It isn't very convenient to get to anytime I want to boot to my SATA SSD. To stop them from reading/writing to one another when I've booted into one, would simply removing the drive letter of the other bootable drive work?


    And here is my Disk Management window:
    Click image for larger version. 

Name:	Disk Management.PNG 
Views:	2 
Size:	45.5 KB 
ID:	145161


    C: in this case is my SATA SSD. E: is my M.2 SSD with my main Windows installation and D: is a data HDD. Looks like my M.2 SSD is missing an EFI partition afterall. What should I do?

    Thanks!
      My ComputerSystem Spec
  6.    22 Jul 2017 #6
    Join Date : Jul 2015
    Posts : 9,381
    Windows 10 Pro

    Just build an EFI System Partition on on the m.2 SSD. I'll post instructions when I get out of the hot tub :-).
      My ComputerSystem Spec
  7.    22 Jul 2017 #7
    Join Date : Jul 2015
    Posts : 9,381
    Windows 10 Pro

    Here's my disk layout, I will be adding an EFI System Partition to my Disk 0. You will have to adjust a few of the commands to match your drive # and drive letter of the Windows you want to boot.

    Click image for larger version. 

Name:	Disk Management.png 
Views:	1 
Size:	31.6 KB 
ID:	145196

    I ran these commands in a Command Prompt (Admin). I believe they will also work in a PowerShell (Admin):

    Code:
    Microsoft Windows [Version 10.0.10586]
    (c) 2015 Microsoft Corporation. All rights reserved.
    
    x:\windows\system32>diskpart
    
    Microsoft DiskPart version 10.0.10586
    
    Copyright (C) 1999-2013 Microsoft Corporation.
    On computer: MININT-KDT67KV
    
    DISKPART> list disk
    
      Disk ###  Status         Size     Free     Dyn  Gpt
      --------  -------------  -------  -------  ---  ---
      Disk 0    Online          447 GB  7168 KB        *
      Disk 1    Online          931 GB  1024 KB        *
      Disk 2    No Media           0 B      0 B
    
    DISKPART> select disk 0
    
    Disk 0 is now the selected disk.
    
    DISKPART> list part
    
      Partition ###  Type              Size     Offset
      -------------  ----------------  -------  -------
      Partition 1    Reserved            16 MB  1024 KB
      Partition 2    Primary            447 GB    23 MB
    
    DISKPART> select part 2
    
    Partition 2 is now the selected partition.
    
    DISKPART> shrink desired=100
    
    DiskPart successfully shrunk the volume by:  100 MB
    
    DISKPART> create partition EFI
    
    DiskPart succeeded in creating the specified partition.
    
    DISKPART> format fs=fat32 quick
    
      100 percent completed
    
    DiskPart successfully formatted the volume.
    
    DISKPART> assign letter=z
    
    DiskPart successfully assigned the drive letter or mount point.
    
    DISKPART> exit
    
    Leaving DiskPart...
    
    x:\windows\system32>bcdboot C:\Windows /s z: /f UEFI
    Boot files successfully created.
    
    x:\windows\system32> exit
    Notes about some of the commands:
    Select Disk # <- Select the disk # of the disk you want to make bootable.
    Select Part # <- Select the partition # of the Windows partition that is occupying all the space on the drive
    bcdboot C:\Windows /s z: /f UEFI <- Change the C: to the current drive letter assigned to the Windows that you want to boot.

    After the commands are completed, you will probably need to enter you UEFI setup when restart your computer to set it to boot from the new Windows Boot Manager on the drive you want to boot from. After you are boot from the desired drive, if the new EFI System Partition has a drive letter assigned to it, you can (and should) remove that drive letter from it in disk management.
      My ComputerSystem Spec
  8.    26 Jul 2017 #8
    Join Date : Oct 2014
    Posts : 19
    Windows 10 Pro
    Thread Starter

    Quote Originally Posted by NavyLCDR View Post
    Here's my disk layout, I will be adding an EFI System Partition to my Disk 0. You will have to adjust a few of the commands to match your drive # and drive letter of the Windows you want to boot.

    Click image for larger version. 

Name:	Disk Management.png 
Views:	1 
Size:	31.6 KB 
ID:	145196

    I ran these commands in a Command Prompt (Admin). I believe they will also work in a PowerShell (Admin):

    Code:
    Microsoft Windows [Version 10.0.10586]
    (c) 2015 Microsoft Corporation. All rights reserved.
    
    x:\windows\system32>diskpart
    
    Microsoft DiskPart version 10.0.10586
    
    Copyright (C) 1999-2013 Microsoft Corporation.
    On computer: MININT-KDT67KV
    
    DISKPART> list disk
    
      Disk ###  Status         Size     Free     Dyn  Gpt
      --------  -------------  -------  -------  ---  ---
      Disk 0    Online          447 GB  7168 KB        *
      Disk 1    Online          931 GB  1024 KB        *
      Disk 2    No Media           0 B      0 B
    
    DISKPART> select disk 0
    
    Disk 0 is now the selected disk.
    
    DISKPART> list part
    
      Partition ###  Type              Size     Offset
      -------------  ----------------  -------  -------
      Partition 1    Reserved            16 MB  1024 KB
      Partition 2    Primary            447 GB    23 MB
    
    DISKPART> select part 2
    
    Partition 2 is now the selected partition.
    
    DISKPART> shrink desired=100
    
    DiskPart successfully shrunk the volume by:  100 MB
    
    DISKPART> create partition EFI
    
    DiskPart succeeded in creating the specified partition.
    
    DISKPART> format fs=fat32 quick
    
      100 percent completed
    
    DiskPart successfully formatted the volume.
    
    DISKPART> assign letter=z
    
    DiskPart successfully assigned the drive letter or mount point.
    
    DISKPART> exit
    
    Leaving DiskPart...
    
    x:\windows\system32>bcdboot C:\Windows /s z: /f UEFI
    Boot files successfully created.
    
    x:\windows\system32> exit
    Notes about some of the commands:
    Select Disk # <- Select the disk # of the disk you want to make bootable.
    Select Part # <- Select the partition # of the Windows partition that is occupying all the space on the drive
    bcdboot C:\Windows /s z: /f UEFI <- Change the C: to the current drive letter assigned to the Windows that you want to boot.

    After the commands are completed, you will probably need to enter you UEFI setup when restart your computer to set it to boot from the new Windows Boot Manager on the drive you want to boot from. After you are boot from the desired drive, if the new EFI System Partition has a drive letter assigned to it, you can (and should) remove that drive letter from it in disk management.
    Thanks so much! Unfortunately I couldn't get this to work (wouldn't let me create a partition for whatever reason) so I just reinstalled Windows on each drive, making sure all other drives were disconnected each time. But for some reason I couldn't get the screen that lets you choose which OS to select to come up, and on each installation Windows didn't detect the other one. In my BIOS I have two boot managers for the two drives, not sure if it's supposed to be that way or that's the reason why it wasn't working. I think I fixed it but I just wanted to make sure if this was the right way.

    I tried Dual Boot Repair but that didn't fix it. On each installation I installed EasyBCD and added a new entry, selecting the drive path of the other installation. It worked but it would sometimes skip the OS selection screen. I guessed I only needed to do this on my main drive so I deleted the other entry on my other installation.

    Now it seems to be working but I have one last question. When I reach the OS selection screen and click on the other installation, the computer restarts and loads that Windows. But if I click the default choice, it doesn't have to restart and just loads into Windows right away. I guess that's because the OS select screen is on my main drive? Is that what should be happening and is there a way to make it so it doesn't have to restart when I select the other OS?


    Thank you so much for all your help.
      My ComputerSystem Spec
  9.    26 Jul 2017 #9
    Join Date : Jul 2015
    Posts : 9,381
    Windows 10 Pro

    Windows did not ask you which version you wanted to install because your computer has a product key for Windows stored in UEFI firmware, setup picked up that product key and used it to install the matching version and activate it.

    Your booting operations is the normal way UEFI dual booting works.
      My ComputerSystem Spec
  10.    26 Jul 2017 #10
    Join Date : Oct 2014
    Posts : 19
    Windows 10 Pro
    Thread Starter

    Quote Originally Posted by NavyLCDR View Post
    Windows did not ask you which version you wanted to install because your computer has a product key for Windows stored in UEFI firmware, setup picked up that product key and used it to install the matching version and activate it.
    Your booting operations is the normal way UEFI dual booting works.
    So because Windows detected the same product key for both installations, it thought this was one installation and that's why it wouldn't detect the other operating system and show the OS selection screen until I manually added an entry in EasyBCD? And that OS selection screen is part of the Windows installation of that drive, so if I select a Windows installation on another drive it'll always restart the computer first? Am I understanding this right?
      My ComputerSystem Spec

 


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