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I would need some support one a boot issue with my Windows 10 system.

I bought a larger SSD some time ago and reinstalled Windows 10 on the new SSD. It seems it was a big mistake to do the installation, during the old SSD was still in the system. During boot still the old SSD is used but starts Windows on the new SSD. I want to remove the old SSD now, but it will not boot without it.

I am also not sure if this can be done easily, because of the Recovery and EFI System Partition is on the old SSD. Disk4 is the new one, Disk 5 the old one:

enter image description here

Would it be possible to fix it that way:

  • shrink the Disk4 Win 10 Partition with the Disk Management tool.
  • Move it the end of the free space (can this be done with the Disk Management tool?)
  • Create / Copy over a recovery partition (is this possible?)
  • Create / Cop over the EFI System partition (is this possible?)
  • Crate the BootManager stuff with bcdedit

All of that without loosing the installation / data on the Disk 4.

I would know what to do on Linux, but I am not that certain on Windows anymore... :)

Thanks for your support.

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7
  • Yes, you've made the typical mistake people do when they don't understand UEFI. Now, although there are Windows tools for what you want to do, reinstalling with only the new drive connected/enabled is by far much easier and probably faster. Later you can reconnect/re-enable the old drive and copy over your olod files or simply reformat it for other usages.
    – user931000
    Commented Dec 11, 2019 at 17:43
  • I don't think that reinstallation is required. It may be enough to reduce C, leaving, say, 600 MB of unallocated space, then disconnect disk 5 and do Startup Repair on disk 4.
    – harrymc
    Commented Dec 11, 2019 at 19:56
  • @harrymc Sounds like a really good idea, but I'll leave 2GB of unallocated space at the beginning, just to be absolutely sure.
    – Diblo Dk
    Commented Dec 11, 2019 at 20:10
  • This might help - link.
    – harrymc
    Commented Dec 11, 2019 at 20:13
  • @GabriellaGarcia regarding UEFI: guilty for sure. That's stuff I need about once a year and forget from occasion to occasion... But really want to avoid to reinstall.
    – user375251
    Commented Dec 12, 2019 at 11:58

1 Answer 1

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5

After ignoring this issue for ages (nearly one and a half year obviously), I had a reason to bite the bullet and try again. I really needed the other SSD to install Proxmox and a VM.

The solution had been to create a new EFI partition on the SSD with the current/active Windows 10 installation. First I had to boot from the old installation. A recovery CD/DVD or USB key will do as well.

To create a recovery drive:

  • Press the windows key and type: create recovery drive and select. Enter admin password
  • select back up system files to the recovery drive and click next
  • connect a USB driver and click next
  • click create and wait a bit
  • restart and enter the BIOS /EFI
  • look out for boot options and select the newly create USB key
  • save & exit

Now your system should reboot from the USB key. If not, try to use a USB connector directly on your motherboard.

To get some space on the SSD for the EFI partition we shrink the main partition, create a new EFI partition and write a bootloader to it by doing following:

  • Start a terminal with SHIFT-F10 during setup.
  • open diskpart, some more info
  • list all the available disks with list disk
  • select disk X, X is the one where the desired Windows 10 installation is located.
  • list partition
  • select partition N, the one to be shrinked
  • shrink desired=500, let's shrink it by 500MB
  • create partition EFI size=200
  • format quick fs=fat32 label="System", or maybe label=EFI if you like better?
  • create partition msr size=123
  • exit
  • bootrec /fixboot
  • bcdboot c:\Windows /s b: /f all, some more infos if needed.

For me this worked like a charm. Sometimes the pressure needs to be big enough to form diamonds. :)

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3
  • 1
    I know this is an old post, but I wanted to add something that I had struggled with: Make sure your actual windows install partition is mounted as C. I kept getting errors from bcdboot because, when I booted from a recovery disk, it mounted my old Windows partition (because I foolishly never formatted it) as C. in diskpart, find and select the volume by 'list volume' and select volume <x>, then remove letter=C. After that, find and select your install volume and assign letter=C. After that, you'll be able to run the last command in this post.
    – Spice
    Commented Jul 13, 2022 at 17:53
  • (on win 11) bootrec /fixboot gave me access denied, and I had to go into diskpart and assign the newly created System/EFI partition letter B to get the last bcdboot command to work, but after that all is perfect :)
    – Whisk
    Commented Jul 24 at 21:47
  • entered here just to say that this is the most complete answer!!! thanks a lot
    – Victor Leal
    Commented Aug 3 at 1:03

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