In some cases, the drives were not formatted at all. Most flash drives that you can purchase are preformatted in the Windows format (because there are more PC users than Mac users).
It is possible that the drive was not formatted in a disk format compatible with macOS. There are two special cases when a USB drive may not be accessible, but not because it was corrupted. How To Fix Unreadable USB Flash Drive On Mac Verify the USB drive was formatted for compatibility with macOS However, before fixing the problem, check if the drive was correctly formatted. After selecting the drive in the Disk Utility, click on the First Aid button to verify the device. MacOS has a built-in tool that can help fix an unreadable USB flash drive on Mac: Disk Utility. If the USB flash drive appears to be corrupted, e.g., when Mac cannot detect it or refuses to mount the drive, make sure that it was properly prepared. However, more often than not, the problem is not with the device itself, but how we use them. They can be damaged or have data corrupted. And every once in a while, this transfer method fails because flash drives are physical devices. Flash, or thumb, drives are a great way to transfer data between multiple computers.
