Unable to reformat thumb drive

Claude Crider wrote:

Running Catalina 10.15.7 on a MacBook Pro (16-inch, 2019).

I have used this method in the past to reformat a thumb drive from MS-Dos to macOS, so don’t know why it’s not working in this case.

I have a thumb drive that came formatted in MS-DOS. I wanted to reformat the drive to be Mac compatible.

I inserted the thumb drive and opened Disk Utility. I highlighted the thumb drive and clicked Erase in the tool bar. It asked me how I wanted to reformat it, and I chose macOS Extended.

It worked for awhile and finally threw an error…’the operation was unable to complete’ (as best I can remember).

Now in Disk Utility it sees the drive, but it is greyed out with message: “disk2S1 USB External Physical Volume - Mac OS Extended”, Not Mounted.

When I remove the drive and then plug it back in, a pop-up window appears with the message:

“The disk you inserted was not readable by this computer.” The choices are Initialize, Ignore, Eject.

If I pick Initialize, the pop-up window disappears but nothing happens, and Disk Utility still shows it greyed out and says “Not Mounted”.

A lot of trouble I know for a silly thumb drive, but this doesn’t add up to me and I’m just curious to see if anyone has any ideas about how to complete this reformat.

Thanks!!

Disk Utility>View>Show All Devices

erase/Reformat/initilize the parent USB drive—partition map: GUID / file format: apfs (or HFS+ if that is what you want.)

Erase and reformat a storage device in Disk Utility on Mac

https://support.apple.com/guide/disk-utility/erase-and-reformat-a-storage-device-dskutl14079/19.0/mac/10.15

From the Terminal.app copy and paste:

diskutil list external

https://osxdaily.com/2013/05/13/mount-unmount-drives-from-the-command-line-in-mac-os-x/

https://apple.stackexchange.com/questions/305071/force-mounting-an-external-disk-that-is-not-recognized

you can see more from Terminal, copy and paste:

 man mount | more

A typical thumb drive, right out of its packaging is formatted as FAT32, which is compatible with macOS, Windows, and Linux without needing any reformat. If you plan to copy files of 4GB or larger to it, then it would need to be reformatted as exFAT retaining the same preceding multi-platform compatibility — without the FAT32 single file size limit.

What happens if you click on mount?