External drives malfunction

Charles Murphy · 12 Jun 2022

I'm Charlie From New York, and I'm new to this forum. I use Windows 10 on my Dell laptop. For several years, I have had six external drives for archiving my music and movies. Recently, all six ceased to operate at the same time. When I tried to open them individually, I received the same message: "The last USB device you connected to this computer malfunctioned, and Windows does not recognize it." When I re-started my computer and re-connected the drives, the same thing happened. I was told my devices may not be working properly. This happened all of a sudden, and to all drives at the same time! Could something have triggered this? Is there a way to salvage the drives?

bobkn · 12 Jun 2022

The obvious suggestion is to try the drives on another PC. I hope that you have access to one.

Berton · 12 Jun 2022

I couldn't tell by images I found on the Internet but both of my Inspiron 15R Notebooks have easily-removed batteries, have seen times where it help to remove the power adapter and the battery, press the Power button to drain off residual power then put everything back and try again. Sometimes it's important as to which USB port/s being used, 2.0 or 3.0. I also keep on hand self-powered USB 2 and 3 Hubs so only have to use one port on the computer.

RickC · 12 Jun 2022

This may be down to how Windows stores info in the registry about attached USB devices. (There's an apparent limit to how many record entries it can store. Once that limit is reached, Windows stops being able to enumerate the attachment of USB devices, even if they have been attached before.)

Rather than fiddle with the registry, try this:

1. Physically disconnect all your external USB hard disks.

2. Download/unblock/unzip Nir Sofer's small, free, portable USBDeview (make sure that you choose correctly between x32/x64 versions) then right-click on the USBDeview executable and choose Run as administrator.

3. Sort on the Device Type column then select all entries showing as Mass Storage (and where the Connected column is showing No).

External drives malfunction-usbdeview_mass_storage.png

4. Right-click on the selected entries and choose Uninstall Selected Devices (or from the File menu).

This will remove the history entries of attached Mass Storage devices stored in the registry.

5. Re-boot (so your PC re-reads the 'local machine' registry hive in full).

6. Re-attach your external USB drives. Windows should enumerate them and will create new 'attached' history entries in the registry.

Post back to let us know whether this fixed the issue.

Hope this helps...

Charles Murphy · 12 Jun 2022

Thanks so much to RickC for his help in getting my external drives back in working order. I sent a longer message to your Reputation folder.
Charlie From New York

RickC · 12 Jun 2022

Thanks for posting back. I'm glad the use of USBDeview worked for you.

TL:DR

For an explanation, I noticed an apparent limit years ago when prepping hundreds of new Garmin SatNavs in work. I thought I'd run into a bad batch of them until I realised that they were recognised by other PCs. This is how I found out how useful USBDeview can be, particularly in clearing out old entries under 2 specific registry keys.

I found that Windows’ enumeration of USB-attached mass storage devices only ever adds a new registry entry based on the device’s vendor/product ID (i.e. HardwareID) and ClassGUID. It does not ever remove any previous entry from the enumeration list of entries stored under:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\USB

If you move the device from one USB port to another then the device’s HardwareID and ClassGUID are recorded as entries under:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\USBSTOR

Whilst drive letter assignment to devices is usually dynamic, recording of enumerated USB-attached devices is apparently absolutely static. The list of entries just grows and grows to a point where an apparent limit is reached... and Windows either just stops recognising newly-attached USB devices (even if they have previously been enumerated/recognised/identified before in the exact same USB port) OR shows them in Device Manager as Unknown device OR recognises them but stops assigning them a drive letter.

I have no idea what the limit is, nor whether it varies depending on other factors (hive size, registry fragmentation, drive letter pointer stored at HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices\DosDevices, etc.). I just know from experience that removing old entries under these two registry keys can restore Windows' enumeration... and that USBDeview is a very easy way to accomplish this rather than revert to manual removal using the Registry Editor or by PowerShell automation.

External drives malfunction

External drives malfunction

External drive malfunction.