how access efi partition on removeable drive for read-write of files

I would like to access the files on the efi partition of a REMOVEABLE DRIVE in order to modify the customize the content of one of the files...
Is this possible

assigning a drive letter fails with diskpart as it does not assign letters to partitions on removeable disks

The partition is hidden, can be seen on disk management but no options available at all on right click

Thanks for any help on this

I have used Diskpart to assign partition letters on removable drives.


diskpart
list disk (it will list all drives. Identify the USB drive number)
select disk n (replace n by the USB drive number obtained with list disk)
list part (it will list all partitions. Identify the EFI partition number)
select part m (replace m by the partition number obtained with list part)
assign letter=w
exit (to exit diskpart)

Thanks cereberus and Paul Black: That was really easy

Megahertz: thanks but even diskpart on win 11 does not permit the user to assign drive letters to partitions that are hidden and protected on a removeable disk

Megahertz said:

I have used Diskpart to assign partition letters on removable drives.


diskpart
list disk (it will list all drives. Identify the USB drive number)
select disk n (replace n by the USB drive number obtained with list disk)
list part (it will list all partitions. Identify the EFI partition number)
select part m (replace m by the partition number obtained with list part)
assign letter=w
exit (to exit diskpart)

On a USB drive Diskpart cannot assign letters to EFI partitions.

Code:

Microsoft Windows [Version 10.0.19044.1706]
(c) Microsoft Corporation. All rights reserved.

C:\Windows\system32>diskpart

Microsoft DiskPart version 10.0.19041.964

Copyright (C) Microsoft Corporation.
On computer: NT-J6TSR

DISKPART> list disk

  Disk ###  Status         Size     Free     Dyn  Gpt
  --------  -------------  -------  -------  ---  ---
  Disk 0    Online          476 GB  1024 KB        *
  Disk 1    Online           14 GB      0 B

DISKPART> sel disk 1

Disk 1 is now the selected disk.

DISKPART> list part

  Partition ###  Type              Size     Offset
  -------------  ----------------  -------  -------
  Partition 1    Primary             14 GB  1024 KB
  Partition 2    System            1024 KB    14 GB

DISKPART> sel part 2

Partition 2 is now the selected partition.

DISKPART> assign letter=w

Virtual Disk Service error:
The operation is not supported on removable media.

DISKPART>

But you can overcome the problem by using the volume instead.

Code:

C:\Windows\system32>diskpart

Microsoft DiskPart version 10.0.19041.964

Copyright (C) Microsoft Corporation.
On computer: NT-J6TSR

DISKPART> list vol

  Volume ###  Ltr  Label        Fs     Type        Size     Status     Info
  ----------  ---  -----------  -----  ----------  -------  ---------  --------
  Volume 0     H                       DVD-ROM         0 B  No Media
  Volume 1     C   Win10        NTFS   Partition    476 GB  Healthy    Boot
  Volume 2         RECOVERY     NTFS   Partition    499 MB  Healthy    Hidden
  Volume 3                      FAT32  Partition    100 MB  Healthy    System
  Volume 4     D   Win10XPE_x6  NTFS   Removable     14 GB  Healthy
  Volume 5         UEFI_NTFS    FAT    Removable   1024 KB  Healthy

DISKPART> sel vol 5

Volume 5 is the selected volume.

DISKPART> assign letter=w

DiskPart successfully assigned the drive letter or mount point.

DISKPART>

MaloK said:

On a USB drive Diskpart cannot assign letters to EFI partitions.

Code:

Microsoft Windows [Version 10.0.19044.1706]
(c) Microsoft Corporation. All rights reserved.

C:\Windows\system32>diskpart

Microsoft DiskPart version 10.0.19041.964

Copyright (C) Microsoft Corporation.
On computer: NT-J6TSR

DISKPART> list disk

  Disk ###  Status         Size     Free     Dyn  Gpt
  --------  -------------  -------  -------  ---  ---
  Disk 0    Online          476 GB  1024 KB        *
  Disk 1    Online           14 GB      0 B

DISKPART> sel disk 1

Disk 1 is now the selected disk.

DISKPART> list part

  Partition ###  Type              Size     Offset
  -------------  ----------------  -------  -------
  Partition 1    Primary             14 GB  1024 KB
  Partition 2    System            1024 KB    14 GB

DISKPART> sel part 2

Partition 2 is now the selected partition.

DISKPART> assign letter=w

Virtual Disk Service error:
The operation is not supported on removable media.

DISKPART>

But you can overcome the problem by using the volume instead.

Code:

C:\Windows\system32>diskpart

Microsoft DiskPart version 10.0.19041.964

Copyright (C) Microsoft Corporation.
On computer: NT-J6TSR

DISKPART> list vol

  Volume ###  Ltr  Label        Fs     Type        Size     Status     Info
  ----------  ---  -----------  -----  ----------  -------  ---------  --------
  Volume 0     H                       DVD-ROM         0 B  No Media
  Volume 1     C   Win10        NTFS   Partition    476 GB  Healthy    Boot
  Volume 2         RECOVERY     NTFS   Partition    499 MB  Healthy    Hidden
  Volume 3                      FAT32  Partition    100 MB  Healthy    System
  Volume 4     D   Win10XPE_x6  NTFS   Removable     14 GB  Healthy
  Volume 5         UEFI_NTFS    FAT    Removable   1024 KB  Healthy

DISKPART> sel vol 5

Volume 5 is the selected volume.

DISKPART> assign letter=w

DiskPart successfully assigned the drive letter or mount point.

DISKPART>

Always learning something new.