Why is my external hard drive not showing up after the macOS Tahoe update?

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1

After updating to macOS 26 Beta 3, my external hard drive is no longer showing up on my Mac. i dont know why…it doesn’t appear in Finder, on the Desktop, or in Disk Utility (though sometimes it flickers briefly there). The drive powers on and works fine on another computer. I’ve tried different USB ports/cables (including direct ports, no hubs).
System: MacBook Air M3, macOS Tahoe
Has anyone else experienced their external hard drive not showing on Mac after the macOS Tahoe update? Any specific fixes or settings changed in Tahoe that could cause this? Solutions beyond basic troubleshooting would be greatly appreciated!

Thanks!

2

@Daniel23333 Sounds like your issue is the Beta version of macOS Tahoe and not the USB drive itself. I would suggest to keep the beta versions updated all the way into the final release of macOS 26 Tahoe access the issue then.

3

Same problem here with the full release of macOS 26. A USB stick is showing up in the system report but not in the finder or diskUtility.

Interestingly, it does show up after waiting for around 20-30 minutes. Formatting the drive does not help. The stick works well with Windows and even ios 26.

4

@maxwell1 It would help to know which Make, Model, Capacity, and Format of USB Flash drive and the Mac Hardware being used.

Have you checked our knowledge base articles?
( Get Support for Your SSDs and Flash Products | Sandisk )

Have you opened a Support Case?
If not, contact SanDisk Technical Support for assistance.
( Contact Support | Sandisk )

5

It’s a SanDisk Ultra Dual Drive Luxe USB Type-C 256 GB. So far I tried formatting it to APFS (both encrypted and not encrypted), exFAT, and MacOS Extended.

edit: I also tried:

  • first aid → no issues found
  • trying with a new user → same problem
  • formatting it on a windows machine → same problem
  • trying different ports and a USB hub → same problem
  • mounting with the terminal is not possible, as it is not detected as a drive
6

Like @SBrown mentioned, this really looks like an issue with the Tahoe beta itself, not the drives. From what I can tell, macOS is detecting the hardware for a split second, but then fails to mount it.

What I suggest is, if your drive is formatted NTFS or another less common file system, try reformatting it to exFAT or HFS+ on another computer to check.

7

You may try the follwing steps to fix an external drive not showing on macOS Tahoe:

  1. Adjust Finder Setting

    • Open Finder > Click Finder on the top menu > Settings.

    • Click General, and tick External disks.

  2. Downgrade macOS
    If the problem appeared after an update, consider temporarily downgrading to a previous stable version.

  3. Reset NVRAM and SMC
    Reset NVRAM: Shut down → Turn on → Hold Option + Command + P + R for about 20 seconds.
    Reset SMC: Follow Apple’s guide depending on your Mac model.

  4. Repair the Drive Using Disk Utility
    Open Disk Utility → Select the drive → Click “First Aid” to verify and repair.

  5. Manually Mount the Drive in Terminal
    Open Terminal → Use diskutil list to find the drive identifier → diskutil mount /dev/diskX (replace X with your disk number).

Related: How to Fix macOS 26 Tahoe External Drives not Showing or Mounting

8

I have the same issue. My thumb drive has two ends, one type C and one type A. My workaround was to use the type A in a connected monitor (hub).

9

Interesting, a monitor hub worked indeed. But just once. It’s like the USB stick is corrupting all the ports I plug it into xD Does it work reliably for you? For me it stopped working the second using the USB stick with the hub …