If you are trying to restore a boot using Windows 10/11 installed on GPT partition from the command line (bootrec /fixboot) in recovery mode of the installation media and getting the error “Access denied”, do the following:

  1. Run the commands
    diskpart
    list volume

    looking for the number of FAT32 partition with the EFI bootloader, and also current letter of our system’s drive C (might be another or also can be not assigned)

  2. Choosing partition with the bootloader an assigning the letter:
    select volume N
    assign letter=L

    Instead of N needs to use the number of the partition and instead of L any currently not used drive letter.

  3. If the system drive (C) is also without letter, assigning the letter same way
  4. Enter exit to close DISKPART.
  5. Executing the follwong command (use your drive letters instead, C in this example is where the system stored, L – assigned by us letter of the EFI partition)
    bcdboot C:\windows /s L: /f UEFI