

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.

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