Windows 10 will not assign a drive letter when connecting a USB Drive (will not release the drive letter when disconnecting as well)


I have a very strange problem. I just purchased a new Western Digital My Passport 2 TB USB drive. I have formatted the drive in Fat32 (Required for my device).

  1. When I connect the drive the Disk Management application sees the drive but no Driver letter is assigned.
  2. Disk Management reports the drive as a Healthy Active Primary partition.
  3. I right click on the drive and assign a drive letter which works as expected. I can now access the drive via file explorer and read and write files.
  4. If I disconnect the drive, the drive letter remains visible in explorer and changes to "Local Disk"
  5. If I reconnect the drive once again a drive letter is not assigned (original drive letter remains listed as "Local Disk" and is inaccessible). 
  6. I can reassign another drive letter as I did in step 3 above and the issue repeats over and over. Of course each time I have less and less drive letters available to me since the assigned letters never release.
  7. In order to reclaim the drive letters I have to reboot (after disabling fast startup in power options, so hardware is re-initialized during reboot). Once reboot is complete all the "Local Disks" created during this process are removed and the drive letters are once again available for assignment.
  8. This process repeats over and over

Other Observations:

  1. I have another 4TB Western Digital My Passport Ultra drive (formatted in Fat32), that does NOT exhibit this behavior. It works normally
  2. The problematic drive works fine when connecting to my Mac.
  3. All other USB drives and sticks I own do NOT exhibit this behavior.
  4. I confirmed in Diskpart that Automatic mounting of new volumes is enable
  5. I contacted Western Digital and after working with them for a while their assessment was since the drive works when a drive letter is manually assigned and works fine in a Mac the drive is fine, they suspect this is an issue with Windows 10.
  6. As a test I also reformatted the drive using NTFS and the issue still happens

Any assistance is appreciated


Hi CantonVideoMan,

Thank you for writing to Microsoft Community Forums.

I appreciate the time you have taken to resolve this issue. I went through the steps you have performed. However, there are some of the steps which can resolve this issue. I would suggest you to follow these steps and let us know the results.

Method 1: Start the service.  

  1. Press Windows andR key together on your Keyboard.

  2. Type Services.msc and hit enter.

  3. Search for Virtual Disk service.

  4.  Double click on Virtual Disk service, select the startup type as Automatic and click on Start to start the service.

Method 2: Auto mount.

  1. Tap on the Windows key on your keyboard.

  2. Type: command prompt

  3. In the search results list, right-click Command Prompt, and then click Run as Administrator.

  4. When you are prompted by User Account Control, click Continue.

  5. Type the following commands.


    Automount (This command will tell you, if it is enabled or disabled.)

    Automount enable

    Automount scrub (If automount is already enabled, type this command to clear the saved associations of system drive letters.)

    Lastly type: Exit

  6. Restart the computer and plug in the USB now to check external USB drives.


Let us know if you need further assitsnace regarding this issue, we will be happy to assist you regarding this issue.

Hope it helps.  

Roohi Taj S

Microsoft Community - Moderator

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Question Info

Last updated June 22, 2021 Views 25,755 Applies to: