USB flash drive not mounting on Mac, how to fix it?

Posted by Katrina to Mac Data Recovery on March 15th, 2018

When I plugged in my USB flash drive on macOS High Sierra, I can't see it in Finder or Desktop. So I went to Disk Utility, it was there. But it was grayed out and I could not mount it. How can I fix/repair USB flash drive not mounting issue on Mac?

Have similar experience when using USB flash drive on Mac like the above example? Under this circumstance, we can't access the USB flash drive or data stored on it. Don't worry, even though the USB flash drive is grayed out in Disk Utility, we still have ways to fix/repair it. This article will offer us two effective solutions to fix/repair USB flash drive not mounting on Mac.

Common reasons of USB flash drive not mounting issue on Mac

What causes USB flash drive not mounting issue on Mac can be various, such as file system damage, volume header corruption, Disk Utility failure, log file corruption, OS malfunction, sudden system reboot, etc.

How to fix/repair USB flash drive not mounting issue on Mac?

No matter what results in unmountable USB flash drive, it's urgent to fix/repair USB flash drive not mounting issue on Mac. Here below are two helpful solutions:

Solution 1: Repair unmountable USB flash drive with Disk Utility

Disk Utility has a built-in function called First Aid, which is able to repair unmountable USB flash drive. First Aid can check the volume for errors and the repair the volume if necessary. The following is the guidance to repair unmountable USB flash drive with Disk Utility:

Step 1: Launch Disk Utility.

Step 2: Choose the grayed out Seagate/WD external hard drive.

Step 3: Select First Aid in the top center and click Run.

Solution 2: Perform data recovery before reformatting

But sometimes, Disk Utility fails to repair unmountable USB flash drive. In this situation, the best solution is to recover data from unmountable USB flash drive, and then fix USB flash drive not mounting issue on Mac by reformatting.

Step 1: Recover data from unmountable USB flash drive with free Mac data recovery software

As a free and professional data recovery software, iBoysoft Mac Data Recovery is highly recommended. It can recover data from unmountable USB flash drive, recover deleted/lost files from emptied Mac trash, recover data from formatted, inaccessible, corrupted, unmountable, unreadable drive in hard drive, external hard drive, flash drive, USB stick and other storage devices on macOS Mojave 10.14/High Sierra 10.13/macOS 10.12 Sierra‎ and Mac OS X 10.11/10.10/10.9/10.8/10.7.

With 4 simple steps, we can recover data from unmountable USB flash drive on Mac:

1. Download and install iBoysoft Mac Data Recovery on your Mac.

2. Connect USB flash drive on Mac and launch iBoysoft Mac Data Recovery.

Recover data from unmountable USB flash drive on Mac with iBoysoft Mac Data Recovery

3. Select the unmountable USB flash drive and click "Next" button to scan all lost files.

4. Preview the results, choose files we want to recover, and click "Recover" button to get lost data back.

Step 2: Fix USB flash drive not mounting issue on Mac by formatting

After recovering data from unmountable USB flash drive, please reformat it in Disk Utility to fix not mounting issue.

Step 1: Launch Disk Utility from Utilities.

Step 2: Click the icon of unmountable USB flash drive on the left part of the window.

Step 3: Click the Erase function on the top of the Disk Utility window.

Step 4: Complete the related information(name, format, scheme), then click Erase button.

After operating these steps successfully, the unmountable USB flash drive can be used normally.

Still have questions?