External HD not showing up - Catalina problem?

grahame97 Said:

”External HD not showing up - Catalina problem?: [...]Now it does not show up on the desktop. Nor in Disk Utility nor in Terminal.[...] how can I get it to mount so that I might fix it with Disk Utility?[...]”

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Use APFS for the Format Type:

Catalina runs off of APFS format. If it is not popping up, then not being APFS may be the case — it is formatted elsewise. So, use APFS —- transfer this data to a new drive (or upload to iCloud, if enough storage). Once transferred, format it to APFS in Disk Utility.

Mount this in Recovery Mode:

Try booting into into Recovery Mode (Hold Down: [command + R] keys upon boot). Then go into Disk Utility, and mount it in there.

But, Before the Format... Two Thoughts:



• Reset the SMC and your NVRAM:

Sometimes when changes are made to the system(i.e. updates), system configurations (i.e. for USB Ports) become manipulated, technically. So, reset the SMC and NVRAM.

• Scan for Malware:

Start with running a scan for malware, using Malwarebytes for Mac and remove what is found. Perhaps something was installed that made this occur. Remove what is found from the quarantine. Malware is short for: Malicious Software. It makes you computer act in a mislead manor

Downloads:

1. Malwarebytes Anti-Malware for Mac
2. Malwarebytes uninstaller

If neither works, continue with the format.

I'm sorry to say but I don't think the other user quite understood your problem. The drive is, indeed, toast. If it fails to be present in Disk Utility, then there isn't much you can do with it. If you files you need to recover, then you can try recovery software.

General File Recovery

If you stop using the disk it's possible to recover deleted files that have not been overwritten by using recovery software such as Disk Drill, MAC Data Recovery, Data Rescue II, File Salvage or TechTool Pro, and others.  Each of the preceding come on a bootable CD to enable usage without risk of writing more data to the disk. Recovery software usually provides trial versions that enable you to determine if the software would help before actually paying for it. Beyond this or if the drive has completely failed, then you would need to send the drive to a recovery service like Drive Savers, which is very expensive.

The longer the hard drive remains in use and data are written to it, the greater the risk your deleted files will be overwritten. Unfortunately, these programs do not work on SSDs.

Also, visit The XLab FAQs and read the FAQ on Data Recovery.

grahame97 Said:

”Not sure what APFS is but as the HD isn't showing in Disk Utility how would I add or reformat or whatever) the disk if the Air can't see it? (Not sure if it is relevant but it is formatted with Journaled but not Encrypted.)“

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You are welcome.

Catalina Reads APFS Format:

APFS is the file system for Catalina. So, using another Catalina-Installed Mac, see if this disk can be seen. If so, then it is probably dust in the port of this computer somewhere. But the other computer - See If you can erase the partitions. Then, format it once more to APFS, in an option.

Too Old of Mac’s for APFS:

If it is too old of a computer, then formatting it to APFS is not an option. So, format it to Extended (Journalized). Then, plugging it into this Mac, format it with APFS. Once APFS is the format type, then Catalina should see it nice and quick. See if it can now be seen on this Mac.

Security Software Getting in the Way:

I don’t know if you have any Security Software installed, but, if so, then it’s Firewall settings are getting in the way here. And such settings would make it just popup and disappear. So, you’d have to uninstall the software. Use the uninstaller and download it form the developer and nowhere else.

Elsewise, your Hard Drive is Failing - it’s time for a new drive.

The external drive or its enclosure is failing. That's why it doesn't show up in Disk Utility.