An input/output error in Disk Utility usually means your Mac cannot read or write to the drive reliably, and restoring it won't fix the underlying problem

When Disk Utility shows an input/output error during a restore operation, the drive itself is the issue, not the file system. Disk Utility's restore function erases and rewrites the drive's structure — but if the drive hardware cannot reliably send or receive data, the restore will fail partway through or appear to complete while leaving the drive unusable.

The error appears because your Mac is trying to communicate with the drive and getting no response, a garbled response, or a response that doesn't match what it sent. This happens most often with failing drives, loose cables, or drives that have been physically damaged. Restoring the drive will not repair the hardware underneath.

Key Takeaways

  • An input/output error means the drive hardware cannot reliably communicate with your Mac, not that the file system is corrupted.
  • Restoring the drive will not fix a hardware problem, so the error will return even if the restore appears to succeed.
  • Check the cable connection and try a different USB port first, since loose connections cause input/output errors that look like drive failure.
  • If the error persists after trying a different port and cable, the drive is likely failing and should be replaced rather than restored.
  • Do not attempt multiple restore operations on a drive showing input/output errors, as repeated writes can accelerate hardware failure.

Why Disk Utility stops during restore with this error

Disk Utility's restore process writes data in blocks to the drive. At each step, it sends a command, waits for confirmation, and moves to the next block. When an input/output error occurs, the drive either does not respond to the command or responds with corrupted data. Disk Utility detects the mismatch and stops rather than continuing to write to a drive it cannot trust.

The error message itself — usually "Input/output error" or a code like "errno 5" — is macOS telling you the hardware layer failed, not the file system layer. This is why repairing the drive with Disk Utility's repair function also fails. You cannot repair hardware with software.

Check the cable and port before assuming the drive is failing

A loose USB cable or a failing port can produce an input/output error that looks identical to a failing drive. Before you conclude the drive is damaged, try these steps in order.

First, disconnect the drive and inspect the cable where it connects to both the drive and your Mac. Look for bent pins, corrosion, or visible damage. If the cable looks intact, reconnect it firmly — push until you feel resistance. Then try the restore again.

If the error returns, try a different USB port on your Mac. If your Mac has multiple ports, use one on the opposite side of the machine. Some ports share the same controller, so moving to a different controller can tell you whether the port itself is the problem. If the restore succeeds on a different port, the original port is failing and you should avoid using it.

If you have access to a different cable (a friend's external drive cable, for example), try that as well. Cables fail more often than drives do, and a bad cable will produce input/output errors on any Mac it connects to.

What to do if the error persists after trying different cables and ports

If the input/output error continues after you have tried a different cable and a different port, the drive hardware is likely failing. The read/write heads inside the drive may be stuck, the motor may be failing, or the drive's controller board may be damaged. None of these problems can be fixed by restoring the drive.

At this point, your options are limited. You can attempt one more restore using a different Mac if you have access to one — this will tell you whether the problem is specific to your Mac or specific to the drive. If the error appears on a different Mac, the drive is failing.

Do not attempt multiple restore operations on the same drive. Each failed restore attempt writes data to the drive, and repeated writes to a failing drive can accelerate the failure. If you need data from the drive, stop attempting restores and consult a data recovery service instead.

Physical damage and water exposure

If the drive has been dropped, sat on, or exposed to water, an input/output error is expected. External drives are portable, and the impact of a fall can shift the read/write heads or damage the platter inside. Water exposure can corrode the controller board or cause the motor to seize.

If the drive has been physically damaged, do not attempt to restore it. Do not open it yourself unless you are working in a clean room environment — opening a drive in a normal room exposes the platter to dust and air, which will cause when ready and permanent damage. If the drive contains important data, contact a data recovery service. If the data is not critical, the drive should be recycled or disposed of according to your local regulations for electronic waste.

When to replace the drive instead of troubleshooting further

External drives are inexpensive compared to the time spent troubleshooting. If you have tried a different cable and a different port and the input/output error persists, the drive is likely at the end of its life. A new external drive costs between $50 and $150 depending on capacity, and you will have a working drive with a warranty.

If the drive is still under warranty, contact the manufacturer with the error message and the steps you have taken. Some manufacturers will replace a drive showing input/output errors without requiring you to ship the failed drive back. If the drive is out of warranty, replacement is usually the most practical choice.

Frequently Asked Questions

Can I recover data from a drive showing input/output errors?

Yes, but not with Disk Utility. Data recovery services can sometimes retrieve files from a drive with hardware problems, though the cost ranges from $300 to $1,500 depending on the damage. If the data is valuable, contact a recovery service for a quote. If the data is not critical, the drive should be replaced.

Does an input/output error mean the drive is definitely broken?

Not always. A loose cable or failing port can produce the same error. Try a different cable and a different USB port before concluding the drive is broken. If the error persists on a different port with a different cable, the drive hardware is likely failing.

Will repairing the drive in Disk Utility fix the input/output error?

No. Disk Utility's repair function fixes file system problems, not hardware problems. If the drive cannot communicate reliably with your Mac, repair will fail with the same input/output error. The drive needs to be replaced.

Is it safe to keep using a drive that shows input/output errors?

No. A drive showing input/output errors is failing and may stop working entirely without warning. If the drive contains data you need, stop using it and contact a data recovery service. Do not attempt multiple restore operations, as repeated writes can accelerate the failure.

What if the error only happens during restore, not when I copy files normally?

Restore operations write to the entire drive sequentially and stress the hardware more than normal file copying does. An error that appears only during restore suggests the drive is failing but not yet completely unreliable. The drive will likely fail soon. Back up any data you need and plan to replace it.