USB Mass Storage devices not detected

Sometimes USB mass storage devices not detected on your computer or laptops. The pen drives, external hard disks are not detected as it may be blocked by your administrator for security reason.

Platform: Windows

What is the problem?

USB Mass Storage devices not detected:

USB Mass Storage devices not detected

In this article, learn how to enable a USB mass storage device by making minor changes in the windows registry settings.

Identify the problem:

The USB Mass Storage devices not detected as the registry key Start (under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\USBSTOR) value is set to 4. To enable USB Mass Storage devices, need to change this to 3.


Follow the below steps to enable the USB Mass Storage devices.

Open Registry Editor (regedit.exe) program and navigate to the following key in the registry.


USB Mass Storage devices not detected

Double click or right click and select Modify.. menu item on the Start key to modify the value. After doing this Edit registry screen displayed.

USB Mass Storage devices not detected

Change the Start key value.

A) Change the registry value from 4 to 3.
B) Select decimal format.
C) Click on OK to save the changes.

USB Mass Storage devices not detected
You my receive an error message “Cannot edit Start: Error writing value’s new contents” once you click on OK button. To solve this problem further read the article Unable to change the registry key value  to save the changes.

Now see that registry key Start value changed from 4 to 3. It means that USB Mass storage is enabled.

USB Mass Storage devices not detected

Now, insert any USB mass storage device such as Pen drive or External USB hard disk, and it should be detected directly.

– Article ends here –

If you have any questions, please feel free to share your questions or comments on the comment box below.

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