I'm trying to format/erase a USB. I tried with Disk utility and got the error: Couldn't open devide : (~69877)
Then I tried with the Terminal with "diskutil eraseDisk ExFAT USB /dev/disk4" but I get the message:
"Unable to begin erase operation: A writable disk is required (-69772)"
What else can I do?
The “A writable disk is required (-69772)” error is the important part. macOS is seeing the USB device itself as read-only, so changing the erase command or format probably won’t help.
Before doing anything else, copy off anything you still need from the drive, since erasing will destroy its contents.
Then I’d check:
• If the drive or adapter has a physical write-protect switch, make sure it’s unlocked.
• Connect it directly to another USB port, without a hub or adapter if possible.
• In Disk Utility > View > Show All Devices, select the top-level physical USB device, not the volume underneath it, and try Erase again. Apple documents that as the correct way to reinitialize an external device.
If it still reports that the disk isn’t writable, try it on another computer. If it’s read-only there too, that usually points to the USB drive itself failing or having entered a hardware read-only state. In that case there generally isn’t a software erase command that can make it writable again, and I’d replace the drive.
The “A writable disk is required (-69772)” error is the important part. macOS is seeing the USB device itself as read-only, so changing the erase command or format probably won’t help.
Before doing anything else, copy off anything you still need from the drive, since erasing will destroy its contents.
Then I’d check:
• If the drive or adapter has a physical write-protect switch, make sure it’s unlocked.
• Connect it directly to another USB port, without a hub or adapter if possible.
• In Disk Utility > View > Show All Devices, select the top-level physical USB device, not the volume underneath it, and try Erase again. Apple documents that as the correct way to reinitialize an external device.
If it still reports that the disk isn’t writable, try it on another computer. If it’s read-only there too, that usually points to the USB drive itself failing or having entered a hardware read-only state. In that case there generally isn’t a software erase command that can make it writable again, and I’d replace the drive.
Unable to format or erase USB drive on Mac
