Knowledge - Details
Date Added: 1/25/2019
If your Windows won't boot because you messed up the EFI boot partition, and you get "Access is denied" when trying to run bootrec /fixboot from a Windows Install DVD, here is how to manually repair the EFI partition:
1) Boot from your Windows 10 Installation Media
2) Select Repair Your Computer.
3) Select Troubleshoot.
4) Choose Command Prompt from the menu
5) Type in the command: diskpart
6) Type in the command: list disk
7) Note which disk number is your boot drive (usually 0)
8) Type in the command: select disk 0 (or whatever your disk number is)
9) Type in the command: list volume
10) Note which volume is the EFI partition. It's probably 100MB and FAT32.
11) Type in the command: select volume 3 (or whatever its volume number is)
12) Type in the command: assign letter=V
13) Type in the command: exit
14) Now that you have assigned a drive letter to the partition, you can format that EFI partition to wipe it out so it can be recreated from scratch.
15) Type in the command: format V: /FS:FAT32
16) Now the EFI partition is blank so you must recreate it.
17) Type in the command: bcdboot c:\windows /s V: /f UEFI
Now, you can reboot the computer and it should load Windows correctly.
Disclaimer: Everything on this website is written for my own use. I disclaim any guarantees that the procedures and advice listed here are accurate, safe, or beneficial for anyone else. If you attempt to follow any procedures or advice shared here, you do it at your own risk. Part of IT work is knowing how to recover from problems.