exFAT external drives become unreadable on Mac after long Windows use

Hello,


I have been experiencing an ongoing problem with external drives, my MacBook Air M3, and my Windows PC. Whenever I plug an external drive formatted as exFAT into my Windows PC for an extended period of time, and then plug it into my Mac, it will no longer read. Disk Utility will freeze and get stuck on loading disks, and I will have to reconnect the drive to my PC and run the lengthy "Scan & Repair" process just to make it functional again. I have had this issue on two devices: my SanDisk 256GB USB Drive, and my brand-new Samsung EVO SELECT microSD 1TB card. Does anyone know how to fix this so it stops happening? Thank you.

MacBook Air 13″, macOS 26.2

Posted on Dec 27, 2025 11:21 AM

Reply
Question marked as Top-ranking reply

Posted on Dec 28, 2025 5:02 PM

Wackyduck wrote:

So, just to clarify, does this mean the exFAT drivers on macOS are more unstable than before?

I have a couple of exFAT drives which I've used between macOS 13.x-15.x, Windows 10/11, and Linux. I have not encountered any issues although I mainly use those drives on macOS. I also used Disk Utility on macOS to create the exFAT volume.


It is hard to say if there are really any issues because most people seeking help here on the forums don't usually provide all the relevant details for us to properly assess the situation. Plus people tend to install junk third party apps which interfere with the normal operation of macOS which also will cause problems. In addition, many people's external drive issues can be traced to hardware issues.....typically with low end cables (manufacturer supplied cables many times are junk & barely able to work), adapters, & hubs/docks. There are just so many possibilities when assisting people remotely when we can actually see & interact with the system & devices.


Follow @tbirdvet's advice and erase those drives using Disk Utility on macOS. People tend to encounter fewer exFAT file system issues when doing this. USB sticks and SD Cards also tend to have more issues than standard Hard Drives and SSDs.


I will have to reconnect the drive to my PC and run the lengthy "Scan & Repair" process just to make it functional again.

Does the scan report any errors? If so, what were the errors?


Have you tried running the scan before ejecting the drive?


It is possible you have third party software installed on your Windows system that is causing this problem. Anti-virus apps, cleaning/optimizer apps, and third party security software can cause all sorts of odd problems because these types of apps interfere with the normal operation of the OS at a very low level where they can cause the most damage (same applies to macOS as well).


Try booting Windows into Safe Mode (not sure this is done with Win10/11) and try performing the same things that tend to cause a problem with these drives when ejecting them. If the issue does not occur while in Safe Mode on Windows, then most likely third party software on Windows is causing the problem. Try booting macOS into Safe Mode when before you connect the exFAT drive to your Mac to see if this makes any difference.

6 replies
Question marked as Top-ranking reply

Dec 28, 2025 5:02 PM in response to Wackyduck

Wackyduck wrote:

So, just to clarify, does this mean the exFAT drivers on macOS are more unstable than before?

I have a couple of exFAT drives which I've used between macOS 13.x-15.x, Windows 10/11, and Linux. I have not encountered any issues although I mainly use those drives on macOS. I also used Disk Utility on macOS to create the exFAT volume.


It is hard to say if there are really any issues because most people seeking help here on the forums don't usually provide all the relevant details for us to properly assess the situation. Plus people tend to install junk third party apps which interfere with the normal operation of macOS which also will cause problems. In addition, many people's external drive issues can be traced to hardware issues.....typically with low end cables (manufacturer supplied cables many times are junk & barely able to work), adapters, & hubs/docks. There are just so many possibilities when assisting people remotely when we can actually see & interact with the system & devices.


Follow @tbirdvet's advice and erase those drives using Disk Utility on macOS. People tend to encounter fewer exFAT file system issues when doing this. USB sticks and SD Cards also tend to have more issues than standard Hard Drives and SSDs.


I will have to reconnect the drive to my PC and run the lengthy "Scan & Repair" process just to make it functional again.

Does the scan report any errors? If so, what were the errors?


Have you tried running the scan before ejecting the drive?


It is possible you have third party software installed on your Windows system that is causing this problem. Anti-virus apps, cleaning/optimizer apps, and third party security software can cause all sorts of odd problems because these types of apps interfere with the normal operation of the OS at a very low level where they can cause the most damage (same applies to macOS as well).


Try booting Windows into Safe Mode (not sure this is done with Win10/11) and try performing the same things that tend to cause a problem with these drives when ejecting them. If the issue does not occur while in Safe Mode on Windows, then most likely third party software on Windows is causing the problem. Try booting macOS into Safe Mode when before you connect the exFAT drive to your Mac to see if this makes any difference.

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exFAT external drives become unreadable on Mac after long Windows use

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