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Level 2

298 points

Disk Utility cannot erase USB Drive

I'm trying to reformat a USB thumbdrive that I'd previously been using as a Linux boot device.

Unfortunately Disk Utility cannot erase the device.

When I insert the drive, I get a warning that it's not readable:

So I click "Initialize..." which launches Disk Utility. In here, it shows up as "disk4s2" (the disk number can vary if I try a different MacOs device), which doesn't look right to me.

When I try to erase the drive, I get the error "Couldn't modify partition map."

There's no write-protect switch on the thumbdrive. How can I fix this?

iMac with Retina 5K display, macOS High Sierra (10.13), 4GHz Intel i7, 32GB RAM, 3TB Fusion

Posted on Oct 25, 2017 10:17 AM

Best reply

CyberGene

Level 1

20 points

Posted on Nov 30, 2017 3:26 PM

There's a much simpler solution. By default Disk Utility shows only volumes. Apparently this is a volume and can't be erased due to unsupported partitioning scheme. So, from the View menu choose "Show All Devices" and then you will be able to see the actual USB device that holds this volume and erase it.

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Disk Utility cannot erase USB Drive

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