Resize EFI partition

1st Official Post
    • Official Post

    Instead of resizing the original EFI partition (which is risky because it is located at the beginning of the disk), we migrate the system to a new, larger EFI partition.

    1. Create a new EFI partition

    Open an elevated Command Prompt and run:

    Code
    diskpart
list disk
select disk X          (replace X with your system disk)
list partition

    Make sure you have unallocated space available (≥350 MB recommended, 500 MB–1 GB preferred).

    Then create the new EFI partition:

    Code
    create partition efi size=500
format quick fs=fat32 label="System"
assign letter=Z
exit

    Explanation:

    • create partition efi → creates a GPT EFI System Partition
    • fs=fat32 → required by UEFI specification
    • size=500 → 500 MB recommended (adjust if needed)
    • assign letter=Z → temporary drive letter for setup

    2. Generate fresh boot files in the new EFI

    Do not copy the old EFI manually (the BCD file is locked while Windows is running).

    Instead, create new boot files:

    Code
    bcdboot C:\Windows /s Z: /f UEFI

    You should see:

    Boot files successfully created.

    3. Redirect firmware boot manager to the new EFI

    Code
    bcdedit /set {bootmgr} device partition=Z:
bcdedit /set {bootmgr} path \EFI\Microsoft\Boot\bootmgfw.efi

    4. Reboot and verify

    Reboot the system.

    If Windows boots normally, the system is now using the new EFI partition.

    You can confirm with:

    Code
    bcdedit

    5. Cleanup

    After confirming everything works:

    • Delete the old 100MB EFI partition
    • Optionally expand the new EFI partition further
    • Resume BitLocker (if it was suspended)

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