I'm using a SanDisk portable SSD with a Dell XPS 15 9570 running Windows 11. Whenever I try to safely eject it, Windows displays: "Problem Ejecting USB Attached SCSI (UAS) Mass Storage Device. This device is currently in use." I've already restarted the computer and Windows Explorer, and no obvious applications appear to be using the drive. What else could be keeping it connected, and how can I identify the program or process responsible?
3 Answers
You can identify what still has the drive open with a process-inspection utility such as Process Explorer, or by checking active processes in Task Manager. Search for handles associated with the drive letter and close the responsible application before ejecting it.
If you’re certain no files are being copied or written, shutting down Windows completely and unplugging the drive while the computer is off is the safest fallback. Avoid disconnecting it during any read or write operation, since that can damage files or the filesystem.
Third-party antivirus or security software may be scanning the SSD and keeping a handle open. Check whether tools such as Malwarebytes, Norton, McAfee, or similar software are running a scan, then try ejecting the drive again once the scan finishes.

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