At times, Windows tells you it isn’t safe to remove a USB drive because it is in use by an app or a process. The message prompt doesn’t tell you which app or process is using a USB. Here’s how you can see what’s preventing Windows from safely ejecting a USB drive.
There are apps available that can detect which app or process is using a USB but Windows has a built-in tool that can do this. It’s called Event Viewer.
Event Viewer is an app that logs all activities, both user and system, as and when they happen. This app isn’t something the average Windows user will ever access but for system administrators, it’s very useful. This is what you will use to check which app or process is using a USB.
Open Event Viewer. You don’t need administrative rights to access this app. On the left column, expand Windows Logs and select ‘System’ under it. On the right column, select ‘Filter Current Log…’.
The filter lets you narrow down which system events are listed in the Event Viewer’s pane. The USB not ejecting is a system event which is why we’re looking under Windows Logs>System. To find the failed ejection event for the USB, we need to apply a filter.
In the Filter Current Log window, click inside the ‘All Event IDs’ field. Replace the default with the number 225 and click Ok.
A failed USB ejection event has the event ID 225. This will filter out all events and show only those related to a failed USB ejection. Double-click the most recent event to view its details.
The details for the event show which app or process it was that kept the USB from ejecting. Look in the ‘General’ tab and the event will describe what prevented the USB from being stopped. It’s not going to highlight the exact app or process for you.
The screenshot below shows an app ‘Taskmgr.exe’ prevented a USB drive from stopping. Taskmgr.exe is the default Movies & TV app in Windows 10.
If an app is preventing your USB from stopping, make sure you’ve closed all instances of it. If it is a process that is preventing a USB from stopping, things are a little more complicated. It’s never a good idea to force quit a process unless you know for certain what it does. Proceed with caution. If you aren’t sure about quitting a process, consider putting your system to sleep or restarting it and then removing the drive.
This works in Windows 7, 8/8.1, and 10.