Mac mini USB A ports not recognizing exFAT external drives

Question

Level 1

23 points

Mac mini USB A ports not recognizing exFAT external drives

I have a Mac mini M2Pro running Sonoma 14.8.9. It has two USB A ports on the back.

Now I had a little accident and pushed a stereo min jack into one of the ports somewhat cos I couldn't quite see the back of the machine. Now it seems that although the ports can read USB sticks and other peripherals they cannot see my external exFAT formatted drives that I use for archiving files?

Before this mishap I did have trouble getting the Mac mini to read the drives sometimes so I am wondering if it just doesn't like exFAT formatted drives? The lights on the external drives always kept flashing.

Posted on Nov 9, 2026 8:31 AM

Answer 1

Nov 9, 2026 11:16 PM in response to GazzaMataz

macOS might not like some exFAT flavors formatted on Windows or Linux. So do a test with a spare USB drive by erasing it on the Mac:

Select Disk Utility > View > Show All Devices. Then select the topmost device name on that drive (not any volumes under it). Erase the USB drive as exFAT, GUID (or Master Boot Record if that fails the test).

Answer 2

GazzaMataz Author

Level 1

23 points

Nov 10, 2026 8:30 AM in response to GazzaMataz

I did a bit of research into this and it appears that there have been many complaints by MacOS Sonoma users that the system doesn't like exFAT formatted drives and many have had problems reading external drives formatted like this. The way to resolve the issue was to go back to using Ventura, format the drives using APFS or install a newer version of the Mac OS.

I will probably format an old external drive in either APFS or ExFat and see if that works on the two USB ports first. If that don't work I'll upgrade to a newer version of Mac OS. Hopefully I haven't fried the USB ports which I don't think (hope) I have since they wouldn't work at all…

Thanks for all the replies peeps much appreciated!

Answer 3

Nov 10, 2026 5:05 AM in response to GazzaMataz

FWIW, in the past when i plugged in drives that were continually flashing but not mounting usually was one of three things: bad cable, bad drive, power issue.

In the second case, I had found that the drive itself was good but the electronics built into the enclosure were faulty.

In the third case, for bus powered drives, I have found that some were on the edge of of their power draw and a small change (could be anything from physical to firmware) pushed it over the edge of not being able to run properly.

Lastly I bring up the first case. This can relate to the third case and/or relate to data passage. A connector that may be on the edge of tolerances can exhibit random behavior and your erroneous of trying to plug in the wrong thing may have pushed it past the edge.

You may also have shorted USB power lines when trying to plug in the wrong thing. while they do have some protection for this sort of event, its not perfect and may have fried the ports.

Answer 4

Nov 9, 2026 2:44 PM in response to GazzaMataz

GazzaMataz wrote:

Before this mishap I did have trouble getting the Mac mini to read the drives sometimes so I am wondering if it just doesn't like exFAT formatted drives? The lights on the external drives always kept flashing.

macOS knows how to read and write exFAT-formatted volumes. It's the NTFS ones that are read-only unless you install third-party filesystem drivers.