If you're seeing a "device in use" error when trying to safely eject your external hard drive, you need to find out what programs are using your external hard drive so you can close them and remove the drive without data loss. The most common culprit is a File Explorer window or an open file, but sometimes background processes or malware are the cause.
Why you need to find what programs are using your external hard drive
The primary reason you need to identify these programs is the frustrating "device in use" error that prevents safe ejection. Windows and macOS block ejection when any process has an open handle to the drive, protecting your data from corruption. Finding the specific program lets you close it cleanly and safely remove the drive.
Quick fixes before you check running programs
Before diving into advanced tools, try these two simple solutions. First, close all File Explorer or Finder windows that show the contents of your external drive. Second, save and close any open files that are stored directly on the drive. Often, one of these actions is enough to release the lock.
Use Task Manager to find programs using your external hard drive on Windows
Task Manager is the fastest built-in tool for this job. Follow these steps:
- Press
Ctrl + Shift + Escto open Task Manager. - Click the "Processes" tab.
- Click the "Disk" column header to sort processes by disk activity.
- Look for processes with high disk read/write values that correspond to your external drive letter.
The process with the highest disk activity is likely the one using your drive.
Use Process Explorer to find the locking program on Windows
When Task Manager isn't specific enough, Process Explorer from Microsoft's Sysinternals suite provides a definitive answer. This advanced tool lets you search for any handle or DLL that references your drive letter.
- Download and run Process Explorer (no installation required).
- Press
Ctrl+Fto open the "Find Handle or DLL" dialog. - Type your drive letter followed by a colon (for example,
E:) and click "Search." - The results show every process with an open handle to that drive, including the exact file or folder it's using.
You can double-click any result to jump to that process, then close it from the main window.
Use LockHunter for a simple right-click solution on Windows
For a more user-friendly approach, LockHunter adds a right-click option to File Explorer. LockHunter displays all processes holding the drive open and offers options to unlock or terminate them.
Check the Activity Monitor on Mac
Mac users have a built-in tool called Activity Monitor. Here's how to use it:
- Open Activity Monitor (found in Applications > Utilities).
- Click the "Disk" tab at the top of the window.
- Identify processes with high values, these are actively accessing your external drive.
You can select any process and click the "X" button to quit it, but save your work first.
Other reasons your external hard drive won't eject
If no program appears to be using the drive, consider these verified causes. Malware scanning can sometimes lock the drive, so scan it for viruses. Check if the drive is set to "Optimize for Quick Removal" in Device Manager, if so, manual safe removal might not be strictly necessary, but identifying processes is still useful if ejection fails. As a last resort, simply restarting your computer will release all locks and allow safe ejection.
