If you are having trouble getting a USB flash drive or external hard drive to mount on your Mac, here are several things you can try to fix the issue.

If you have to use a flash drive on both Macs and Windows PCs, make sure both systems can read it. Here's how to format the drive correctly.

This step by step guide with images covers how to transfer files between iPhone and Mac with a USB flash drive as well as offering a few alternate options.

Attach the USB flash drive to your Mac and locate its disk icon on your desktop, in a Finder window, or in the Finder sidebar, then right-click (or Ctrl-click) it and select Encrypt " [USB stick ...

A Mac computer with an available USB port. An external drive or flash drive that you want to format. It can be an external hard disk, SSD, flash drive or USB drive.