External drive does not show up (10.15.2)

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External drive does not show up (10.15.2)

I have an external 1 Tb thunderbolt SSD drive from OWC that I have used for TimeMachine backups on my retina MB Air (2019). It worked fine (connected to one of the ports on the machine) under 10.15.1, and has a few backups on it. Recently I went on a trip, and did not take the backup drive with me. While away, I updated to 10.15.2, Now the backup drive does not show up at all: not in the Finder, not in Disk Utility, not as a device on the USB bus in System Report. The drive appears to be fine: I can connect it to another machine (running 10.15.2) and it shows up. Running Disk Utility - First Aid on it on that machine reveals no problems. Similarly, the MB Air's ports seem fine: I can connect my iPhone or iPad using a USB-C to Lightning cable and those devices are seen. Running Apple diagnostics (startup with D) reveals no problems. Resetting NVRAM does no good. Nothing seems to allow this drive to mount. I've tried multiple fixes suggested on the web, with no luck, reinstalled the operating system, still no luck. Help!

MacBook Air 13", macOS 10.15

Posted on Dec 25, 2019 11:32 AM

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Answer 1

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HWTech

Level 9

60,098 points

Dec 26, 2019 5:44 PM in response to YaLinguist

I'm not familiar with the latest MBAirs, but if there are multiple USB-C ports have you tried them all with the external drive?

Are you connecting the drive directly to the laptop?

Have you tried connecting the drive while booted into Safe Mode?

Does another USB drive or USB stick work on this laptop?

Try booting into Internet Recovery Mode using Command + Option + R. Launch Disk Utility to see if the drive is seen. Within Disk Utility click on "View" and select "Show all devices" to see if the physical drive appears in the left pane of Disk Utility.

Are you using the same USB-C cable when testing the drive on the other computer? Maybe your USB-C cable is bad or you are using just a USB-C USB cable instead of a USB-C Thunderbolt cable. I believe Apple puts a lightning bolt on their USB-C Thunderbolt cables. The USB-C cable provided with your power adapter will not work as it is only a charging cable and only supports USB2 for data.

If you still have problems, then you may need to take the laptop and your external drive to an Apple Store or an Apple Authorized Service Provider to be examined.

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Answer 2

YaLinguist Author

Level 1

9 points

Dec 27, 2019 1:39 PM in response to HWTech

Thanks, but I think I've checked out all of those things. The drive has a built-in Thunderbolt cable (OWC intends it for use on Thunderbolt3 ports), which is the same cable I use to connect it (directly) to the MBA and to the other machine (a 2018 Mac Mini). Other devices, such as my iPad and iPhone, connect to the ports on the MBA (via a USB-C -- Lightning cable) and show up in the System report as connected to the USB bus, while the external drive does not show up either in that way or in DiskUtility (whether run normally at login, in Safe Mode, or in Recovery mode). The drive is getting power from the USB bus, since its light is lit. As far as I can tell, each of the drive and and the MBA is functioning perfectly well, EXCEPT that they won't play together. The only thing I haven't tried so far is to reformat the drive on my other machine, which I'm reluctant to do until someone tells me it's likely to help, because then I would lose the Time Machine backups that were made on the drive before my recent trip.

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External drive does not show up (10.15.2)

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