Problem: Windows Will Not Assign a Drive Letter to a USB Flash Drive

This issue can occur on Windows 8 and Windows 10. You unplug a USB flash drive, plug it back in, and Windows fails to assign a drive letter. That’s a real problem, especially when every other computer handles the same device without issue.

There are three solutions. All of them can work:

1. You can open Disk Management and manually assign a drive letter to the device. This works, but it’s a repetitive and inconvenient fix if the problem happens often.
2. There’s a good chance the driver or registry entry for that device is corrupt. Use the USBScrub tool to remove old USB registry entries. In many cases, this resolves the issue immediately. Download USBScrub
3. Use DiskPart and enable the automount feature.

• Open Command Prompt as Administrator (search for Command Prompt in the Start menu, right-click, and select “Run as administrator”).
• Type diskpart and press Enter.
• At the DiskPart prompt, type automount enable and press Enter.
• Type exit and press Enter.

For solution number one above, Disk Management is essentially the graphical (GUI) version of DiskPart, but with a reduced feature set compared to what DiskPart can actually do.

DiskPart includes dozens of useful commands for managing storage devices. One of the most important is automount, which controls whether Windows automatically assigns drive letters to newly connected volumes.

UPDATE: USB Scrub by Nexcopy now supports Win7, Win10 (32/64bit) and Windows 11

USB Registry Cleaner Tool which is FREE!

Did you know Windows can make over 260 registry entries with a single enumeration of a USB stick? This means for those with multiple flash drives, your registry will get extremely cluttered and bogged down.

With flash drives dirt cheap these days, you’ll find at least a couple dozen going into your computer throughout the year. That would be over 6,240 registry entries.

USB Scrub is a free utility from Nexcopy which performs a deep cleaning of those unused drivers and registry edits.

We gave USB Scrub a try, and it worked great. We went from enumerating a single USB stick in 45 seconds to enumerating that stick in less than 12 seconds.

In addition, if you have a USB stick that doesn’t perform correctly or the Windows OS doesn’t see it, chances are the USB Scrub will clear up those problems and your drive will work once again. This is because a registry entry can become corrupt, and simply clearing it out will resolve your issue.

So let’s take a closer look.

Using RegShot (a free application which takes a snapshot before and after an event and compares only the changed registry values), I took a snapshot before and after a USB stick was connected and ejected. The result was this:

• 78 Registry Keys created
• 183 Registry Values added
• 261 Registry edits in total!

Here is a snapshot. Click the image to get the full text file:

Next, I took a snapshot of the registry before a stick was connected, then ran USB Scrub, then took the second registry snapshot. This is what I got:

• 1 Registry Key added
• 3 Registry Values added

Clearly we have a big difference. Clearly we have a great cleaning tool for USB devices in Windows.

If you have a USB flash drive not working correctly, a slow computer, or you are a heavy user of removable drives, give USB Scrub a try. You’ll see a noticeable difference in USB enumeration.

As a closing note, when the enumeration speed went from 45 seconds to 12 seconds, USB Scrub reported that it cleared over 9,000 registry entries.

USB Scrub is a free utility. There is no malware or spyware.

Unfortunately, USB Scrub only supported Windows XP in the past. The maker, Nexcopy, has now updated support for Windows 7 and Windows 10. (Does not support Windows 8.)

UPDATE: Download link now supports Windows 7 and Windows 10 (32/64bit).

Download USB Scrub. Source: EverythingUSB.com.