at least one volume could not be unmounted

Macs are mistakenly believed to be virus-proof. Some hardware components of your Mac might cause the 'external hard drive not readable' Mac issue. So even if you’ve never experienced issues with external drives, Disk Drill is an essential install for your Mac.

Tip: Tools like Disk Drill - a data recovery app for Mac - will help you save the data stored on the failing disk. One of the most common reasons is disk failure, and it’s also the most unfortunate one because it can happen quite unexpectedly and is impossible to predict. Here are the top five reasons why external drive won’t open on Mac:ĭisk failure. Just click Initialize and you’ll be able to access it. Please note that sometimes the USB not readable Mac error will appear if you connect a new drive. However, every case is unique and we encourage you to go through all the troubleshooting steps instead of assuming you know what has caused the error. We outline a few probable reasons we see most often. There’s no easy way to understand why the error occurs - unless you've had it with the same disk before. Reasons for Mac not reading external hard drive

On macOS Big Sur, the error will read slightly differently: 'the disk you attached was not readable by this computer' - but it’s essentially the same thing. When you connect an external hard drive, a USB, or a SD drive to your Mac, the following error might pop up on the screen: 'the disk you inserted was not readable by this computer.' It usually occurs on macOS High Sierra, Mojave, and Catalina.

Instructions on how to fix it when your Mac won’t read a disk.

Reasons for Mac not reading external hard drive.

In this article, we'll explain how to fix corrupted hard drive, how to make a drive with an incompatible file system readable, and other methods to avoid the error on your Mac. Even more, you can fix the issue with the drive and continue using it. We assure you it’s possible to recover data from that drive even in the worst-case scenarios.

When you have important files on the external drive you're trying to connect, but your Mac shows an error saying 'the disk was not readable' - don’t panic. Get an ever-growing collection of troubleshooting apps.

At least one volume could not be unmounted