How To Rebuild EFI System Partition From Scratch

EFI system partition is a small (100-500 MB) FAT16 or FAT32 partition containing UEFI-compatible Windows Boot Loader and its configuration (BCD registry hive). This partition may also contain other files (e.g. Linux Boot Loaders) in dual-boot configurations.

When UEFI-based computer is powered up, its firmware searches for EFI system partition on all attached storage devices. If EFI system partition does not exist, then computer will not boot.

This article is for people who accidentally deleted or formatted EFI system partition and need to rebuild it from scratch without reinstalling Windows.

This article assumes that computer uses UEFI boot method. Also we have a similar article for computers which use non-UEFI/BIOS/CSM/Legacy boot method.

Contents

1. Solution in a nutshell

  1. Boot into Emergency Boot Kit.
  2. If 100-500 MB EFI system partition does not exist, create it using Emergency Boot Kit Partition Manager.
  3. Format EFI system partition with Emergency Boot Kit Partition Manager to VFAT filesystem.
  4. Change newly created partition type to "EFI System Partition (C12A7328-F81F-11D2-BA4B-00A0C93EC93B)".
  5. Using Emergency Boot Kit File Manager, copy \Windows\Boot\EFI folder from Windows system partition to \EFI\Microsoft\Boot folder on the new EFI system partition; and also copy \Windows\Boot\Fonts folder from Windows system partition to \EFI\Microsoft\Boot\Fonts folder on the new EFI system partition.
  6. Using Emergency Boot Kit File Manager, create \EFI\Boot folder on the new EFI system partition; and also copy \Windows\Boot\EFI\bootmgfw.efi file from Windows system partition to \EFI\Boot\bootx64.efi file on the new EFI system partition.
  7. Verify the result: at least the following files must exist in EFI system partition:
    \EFI\Microsoft\Boot\bootmgfw.efi
    \EFI\Microsoft\Boot\bootmgr.efi
    \EFI\Microsoft\Boot\memtest.efi
    \EFI\Microsoft\Boot\Fonts\wgl4_boot.ttf
    \EFI\Boot\bootx64.efi
  8. Run Emergency Boot Kit Mount & Boot Center to recreate BCD hive from scratch.

2. Creating EFI system partitition

1) Download Emergency Boot Kit and deploy it to USB thumbdrive according to the instructions, then set up your BIOS to boot from USB thumbdrive.

2) Boot into Emergency Boot Kit and run Partition Manager from the main menu:

Rebuild EFI System Partition From Scratch - Run Emergency Boot Kit Partition Manager
Rebuild EFI System Partition From Scratch - Run Emergency Boot Kit Partition Manager

3) Assuming EFI system partition does not exist, create it (otherwise, format it):

Rebuild EFI System Partition From Scratch - Create new system partition
Rebuild EFI System Partition From Scratch - Create new system partition

4) Set its size to 100 megabytes:

Rebuild EFI System Partition From Scratch - Set size of new system partition
Rebuild EFI System Partition From Scratch - Set size of new system partition

5) Set its filesystem type to VFAT and volume label to empty:

Rebuild EFI System Partition From Scratch - Set filesystem type and volume label of new system partition
Rebuild EFI System Partition From Scratch - Set filesystem type and volume label of new system partition

6) EFI system partition was created and formatted successfully:

Rebuild EFI System Partition From Scratch - New system partition created and formatted
Rebuild EFI System Partition From Scratch - New system partition created and formatted

7) Choose an option to edit partition metadata for newly created/formatted partition:

Rebuild EFI System Partition From Scratch - Edit partition metadata
Rebuild EFI System Partition From Scratch - Edit partition metadata

8) Choose newly created/formatted EFI system partition from the list:

Rebuild EFI System Partition From Scratch - Choose EFI system partition
Rebuild EFI System Partition From Scratch - Choose EFI system partition

9) Set GPT partition type to "EFI System Partition (C12A7328-F81F-11D2-BA4B-00A0C93EC93B)":

Rebuild EFI System Partition From Scratch - Setting GPT partition type to C12A7328-F81F-11D2-BA4B-00A0C93EC93B
Rebuild EFI System Partition From Scratch - Setting GPT partition type to C12A7328-F81F-11D2-BA4B-00A0C93EC93B

10) Click Next to apply changes to metadata of newly created/formatted partition:

Rebuild EFI System Partition From Scratch - Applying changes to GPT partition metadata
Rebuild EFI System Partition From Scratch - Applying changes to GPT partition metadata

11) Metadata of newly created/formatted partition has been updated successfully:

Rebuild EFI System Partition From Scratch - Metadata of GPT partition has been updated successfully
Rebuild EFI System Partition From Scratch - Metadata of GPT partition has been updated successfully

12) Quit from Emergency Boot Kit Partition Manager to the main menu:

Rebuild EFI System Partition From Scratch - Quit to the main menu
Rebuild EFI System Partition From Scratch - Quit to the main menu

3. Poplulating EFI system partitition

1) Run Emergency Boot Kit File Manager:

Rebuild EFI System Partition From Scratch - Run Emergency Boot Kit File Manager
Rebuild EFI System Partition From Scratch - Run Emergency Boot Kit File Manager

2) Press Alt+F1 to change disk on the left panel. Choose your Windows system partition from the list (D: in this example):

Rebuild EFI System Partition From Scratch - Choose Windows System Partition On The Left Panel
Rebuild EFI System Partition From Scratch - Choose Windows System Partition On The Left Panel

3) Navigate to Windows folder using arrow keys. Then press ENTER.

Rebuild EFI System Partition From Scratch - Navigate to Windows folder and enter it
Rebuild EFI System Partition From Scratch - Navigate to Windows folder and enter it

4) Navigate to Boot folder using arrow keys. Then press ENTER.

Rebuild EFI System Partition From Scratch - Navigate to Boot folder and enter it
Rebuild EFI System Partition From Scratch - Navigate to Boot folder and enter it

5) Navigate to EFI folder using arrow keys. Then press ENTER.

Rebuild EFI System Partition From Scratch - Navigate to EFI folder and enter it
Rebuild EFI System Partition From Scratch - Navigate to EFI folder and enter it

6) Press Alt+F2 to change disk on the right panel. Choose newly created/formatted EFI system partition from the list (E: in this example):

Rebuild EFI System Partition From Scratch - Choose EFI System Partition On The Right Panel
Rebuild EFI System Partition From Scratch - Choose EFI System Partition On The Right Panel

7) Press F7 to create a new directory. Type in EFI and press ENTER or click OK.

Rebuild EFI System Partition From Scratch - Creating EFI directory
Rebuild EFI System Partition From Scratch - Creating EFI directory

8) Press ENTER to enter EFI directory.

Rebuild EFI System Partition From Scratch - Entering EFI directory
Rebuild EFI System Partition From Scratch - Entering EFI directory

9) Press F7 to create a new directory. Type in Microsoft and press ENTER or click OK.

Rebuild EFI System Partition From Scratch - Creating Microsoft directory
Rebuild EFI System Partition From Scratch - Creating Microsoft directory

10) Press ENTER to enter Microsoft directory.

Rebuild EFI System Partition From Scratch - Entering Microsoft directory
Rebuild EFI System Partition From Scratch - Entering Microsoft directory

11) Press F7 to create a new directory. Type in Boot and press ENTER or click OK.

Rebuild EFI System Partition From Scratch - Creating Boot directory
Rebuild EFI System Partition From Scratch - Creating Boot directory

12) Press ENTER to enter Boot directory.

Rebuild EFI System Partition From Scratch - Entering Boot directory
Rebuild EFI System Partition From Scratch - Entering Boot directory

13) Press TAB to switch to the left panel. Then press and hold INSERT key to select all files and folder on the left panel.

Rebuild EFI System Partition From Scratch - Selecting all files and folder on the left panel
Rebuild EFI System Partition From Scratch - Selecting all files and folder on the left panel

14) Press F5 and ENTER to initiate and confirm file copy operation:

Rebuild EFI System Partition From Scratch - Initiate and confirm file copy operation
Rebuild EFI System Partition From Scratch - Initiate and confirm file copy operation

15) After files and directories are copied, press HOME key to navigate to the top of the list on the left panel, then press ENTER to leave current folder and navigate to the parent folder:

Rebuild EFI System Partition From Scratch - Leaving EFI folder on the left panel
Rebuild EFI System Partition From Scratch - Leaving EFI folder on the left panel

16) Using arrow keys, navigate to the Fonts folder:

Rebuild EFI System Partition From Scratch - Navigating to the Fonts folder
Rebuild EFI System Partition From Scratch - Navigating to the Fonts folder

17) Press F5 and ENTER to initiate and confirm file copy operation for Fonts folder:

Rebuild EFI System Partition From Scratch - Initiate and confirm file copy operation for Fonts folder
Rebuild EFI System Partition From Scratch - Initiate and confirm file copy operation for Fonts folder

18) Fonts were copied successfully:

Rebuild EFI System Partition From Scratch - Fonts were copied successfully
Rebuild EFI System Partition From Scratch - Fonts were copied successfully

19) Press TAB to switch to the right panel, then HOME and ENTER keys to leave current folder. Repeat, so you will end up in the \EFI folder:

Rebuild EFI System Partition From Scratch - In the EFI folder
Rebuild EFI System Partition From Scratch - In the EFI folder

20) Press F7 to create a new directory. Type in Boot and press ENTER or click OK.

Rebuild EFI System Partition From Scratch - Creating Boot directory
Rebuild EFI System Partition From Scratch - Creating Boot directory

21) Press ENTER to enter Boot directory.

Rebuild EFI System Partition From Scratch - Entering Boot directory
Rebuild EFI System Partition From Scratch - Entering Boot directory

22) Press TAB to switch to the left panel and navigate to bootmgfw.efi file using arrow keys:

Rebuild EFI System Partition From Scratch - Navigate to bootmgfw.efi file
Rebuild EFI System Partition From Scratch - Navigate to bootmgfw.efi file

23) Press F5 to initiate file copy operation. Change target file name to \EFI\Boot\bootx64.efi and press ENTER to confirm.

Rebuild EFI System Partition From Scratch - Press F5, change file name to bootx64.efi and confirm
Rebuild EFI System Partition From Scratch - Press F5, change file name to bootx64.efi and confirm

24) Here's how file copying result should look like:

Rebuild EFI System Partition From Scratch - File copying result
Rebuild EFI System Partition From Scratch - File copying result

25) Press F10 or click Quit in the bottom hint bar to quit Emergency Boot Kit File Manager

Rebuild EFI System Partition From Scratch - Quit Emergency Boot Kit File Manager
Rebuild EFI System Partition From Scratch - Quit Emergency Boot Kit File Manager

4. Rebuilding BCD hive from scratch

1) Run Emergency Boot Kit Mount & Boot Center from the main menu:

Rebuild EFI System Partition From Scratch - Run Mount and Boot Center
Rebuild EFI System Partition From Scratch - Run Mount and Boot Center

2) Make sure that Windows Loader in EFI system partition is detected by Mount & Boot Center, and also that your main Windows installation is [x] marked in context of that loader. Then press OK.

Rebuild EFI System Partition From Scratch - Configure Mount and Boot Center
Rebuild EFI System Partition From Scratch - Configure Mount and Boot Center

3) Done. Reboot to Windows.

Rebuild EFI System Partition From Scratch - Done
Rebuild EFI System Partition From Scratch - Done