Error Messages

I/O Device Error on an External Hard Drive: Causes and Fixes

Updated October 2, 2026 •7 min read

“The request could not be performed because of an I/O device error.” It’s one of the most common messages people see when an external hard drive, USB stick, or SD card stops cooperating. “I/O” means input/output — Windows tried to read from or write to the device and the operation failed at the hardware level.

The good news: it’s often a connection problem. The bad news: it’s also an early sign of a failing drive. Here’s how to tell the difference.

Common causes

A bad or loose cable, or a worn USB port.
Not enough power — bus-powered portable drives on a hub or front-panel port.
A failing USB bridge board — the small circuit inside an external enclosure that translates USB to the drive. When it fails, you get I/O errors even if the disk itself is fine.
Driver problems in Windows.
A drive-letter conflict or a disk that isn’t initialized.
A failing drive — bad sectors or weak read heads that can’t complete the request.

Fixes to try, in order

These are all safe for your data.

1. Change the connection

Use a different cable, plug directly into a rear USB port (no hubs or docks), and try another computer. Many I/O errors end here.

2. Reinstall the device driver

Open Device Manager, expand Disk drives, right-click your drive → Uninstall device, then unplug and reconnect it. Windows reinstalls the driver fresh. It’s also worth expanding Universal Serial Bus controllers and doing the same for the USB Root Hub if errors persist.

3. Check Disk Management

Right-click Start → Disk Management. Look at how the drive appears:

Healthy with no letter → right-click → Change Drive Letter and Paths → assign one.
“Not Initialized” or “Unknown” → don’t initialize it if the data matters. See Disk Unknown, Not Initialized.
RAW file system → don’t format it. See RAW drive recovery.

4. Check the drive’s health

Run a SMART check. A rising UltraDMA CRC Error Count points at the cable or bridge. Reallocated, pending, or uncorrectable sectors point at the drive itself.

5. Repair the file system — only if the drive is healthy

If SMART is clean, run chkdsk X: /f from an administrator Command Prompt. Skip this step if SMART shows problems — repair tools write to the drive and add stress.

The external-drive caveat: don’t pull the drive out of its case

When the I/O error is caused by a dead USB bridge, the obvious fix is to remove the bare drive and connect it directly. On many drives, that doesn’t work:

Western Digital My Passport and My Book drives encrypt data in hardware on that bridge board — even if you never set a password. The bare drive reads as gibberish without it. (More on WD drives here.)
Many portable drives (including many My Passport models) have the USB connector soldered directly onto the drive’s own circuit board — there’s no standard SATA connector to plug into.

If the drive is encrypted or has a native-USB board, a bridge failure is a job for a lab that can address the electronics without losing access to the data.

When the I/O error means the drive is failing

Stop and power it down if:

The drive clicks, beeps, or grinds.
It connects, disconnects, and reconnects on its own (see external drive keeps disconnecting).
The error appears after a drop.
SMART shows pending or uncorrectable sectors.

Every extra attempt on a mechanically failing drive lowers the odds of a full recovery.

The bottom line

An I/O device error is a failed conversation between your computer and the drive. Change the cable and port, reinstall the driver, and check Disk Management before anything else. If SMART shows the drive itself is degrading — or it’s making noise — stop troubleshooting and protect the data.

Our hard drive recovery service handles I/O-error drives, failed bridges, and encrypted WD externals for one flat price, with no charge unless we recover your data.