iMac: External drives in Disk Utility, not Finder

Question

Level 1

8 points

iMac: External drives in Disk Utility, not Finder

Hi

None of my external back-up hard drives are recognised or show up in Finder. Connections are directly into the back of the iMac USB port which works and sees USB sticks perfectly.

However, the external back-up hard drives do show in the 'DISK UTILITY' and I have tried 'FIRST AID' and get "Operation Successful" but they still do not show in Finder.

I then ran Restore and got "Restore process has failed. Click Done to continue"

My iMac is (Retina 5K, 27-inch, 2017) macOS Version12.5.1 (21G83)

I have done numerous software updates and I have been unable to access ANY of my external hard drives which all worked perfectly up until about 18 months ago!

Please advise

Thanks

Ed

iMac 27″ 5K, macOS 12.5

Posted on Jun 30, 2026 4:22 AM

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Answer 1

den.thed

Level 10

95,686 points

Jun 30, 2026 6:14 AM in response to Ed_in_London

Go to Finder > Finder Settings... check the "External Disks" boxes in the General and Sidebar sections.

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Answer 2

Old Toad

Level 10

217,588 points

Jun 30, 2026 11:38 AM in response to Ed_in_London

Boot into Safe Mode according to How to use safe mode on your Mac and test to see if the problem persists. Reboot normally and text again.

Note: if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode. This makes it act as a wired keyboard as will assure a successful boot into Safe Mode.

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Answer 3

den.thed

Level 10

95,686 points

Jun 30, 2026 3:05 PM in response to Ed_in_London

Hmm.. lets double check the 320GB external drives Partition Map Scheme and Format.

Connected just the 320GB drive to the iMac and open Disk Utility.

Click on the little View icon box and select Show All Devices.

Select each device in the list and take a screenshot.

Then post a screenshot for each selection.

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Answer 4

den.thed

Level 10

95,686 points

Jun 30, 2026 12:49 PM in response to Ed_in_London

Ed_in_London wrote:

Hi Den

Thanks for replying.

My Finder settings are all ticked as per your examples.

Ed

Hi Ed

What do you have on that 320GB external drive in the screenshot...?

I'm asking because it looks like that external is not formatted correctly for use with a Mac.

If that 320GB external drive was formatted on a PC and the files are from a PC...?

Take it back to the PC and copy the files back to the PC or to another external drive.

Then erase and reformat that external drive ExFat, copy the files back and move it to the Mac.

If you want to erase and format that 320GB external drive to use exclusively with your iMac...?

check out > Initialize an external storage device in Disk Utility on Mac - Apple Support

Just keep in mind that erasing and reformatting will wipe everything on the drive.

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Answer 5

Ed_in_London Author

Level 1

8 points

Jun 30, 2026 1:55 PM in response to den.thed

Hi Den

Well observed the drive did come out of a PC and it was reformated to Mac and was used happily with my iMac until approx 18 months ago along with my other Mac formatted external hard drives which no longer are accessible.

Ed

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