Even if you have closed all documents, a File Explorer window that is displaying the contents of the device can hold a handle to the drive. Simply having the folder open in the background is enough to prevent a lock.
The error message typically occurs when a low-level utility (like a formatting tool or disk manager) requires exclusive access to a drive, but another process is still using a file or handle on that device. Common Scenarios for This Error
echo 1 > /sys/block/sdX/device/delete # SCSI device removal (re-scan required) hdparm --user-master u --security-unlock "" /dev/sdX # (not recommended) Even if you have closed all documents, a
lsof /dev/sdb reveals a stale NFS lock or a process like gvfsd-trash holding the device.
If unmount fails with “target is busy”: Common Scenarios for This Error echo 1 >
: Ensure no File Explorer windows, media players, or documents from that drive are open. Use a Secondary PC
In the world of data management, "locking" is a safety feature. When a file on a hard drive or USB stick is in use—being read, written to, or modified—the operating system places a "lock" on that file or the entire file system. This prevents other processes from simultaneously trying to modify the same data, which could result in corruption. When a file on a hard drive or
To solve the problem, you must first understand the mechanism behind it. Why does an operating system need to "lock" a device in the first place?
Open a different folder on your internal hard drive (e.g., C:\ on Windows or your Home folder on Mac). Do not have any window showing the contents of the problematic device.
If you have a Command Prompt, PowerShell, or Terminal window open that is currently using the device’s drive letter (e.g., D: ), close it.
A program that crashed while accessing the device may not have released its lock. The OS still thinks the file is in use, even though the program is gone.