"Unable to write to the last block of the device"

Thanks for the tip!l Apparently this bug still exists in Yosemite.

After a disconnect mid write to a 64gb usb flash drive, i couldn't reformat or repartition the usb stick from osx and was getting the error: "Unable to write to the last block of the device"

Trying to read or write to the disk resulted in strange behaviors, files showing up instantly with wrong size, files not being able to be deleted, etc. Tried all the OSX based fixes suggested in this thread including recovery partition with no luck and obviously the firewire solution is not possible for a usb flash drive.

Finally tried repartitioning it from a windows 8.1 parallels vm, and it went smooth as butter and now works again. Was able to replicate the issue on a second usb flash drive by disconnecting mid write, exact same issues in osx, this time i repaired it in ubuntu using gparted. So I've verified that both those solutions fix the issue and this can easily happen to a perfectly fine working drive. Hope that helps future visitors with the same issue.

Just happened to me, with a brand new disk. Even cmd-r recovery did nothing for me. In the end I realised that I was connecting the disk to my MaCBook via a USB port multiplier; when I plugged it directly into a usb port of the MacBook, the problem evaporated. So: connection problem?

Thanks so much. This was starting to have me really pulling my hair out.

#arpamac - thanks!!!

Your solution (using diskutil to erase the disk while in recovery mode) worked for me when I was getting "Unable to write to the last block of the device" errors trying to format a microSD card in a macbook pro running El Capitan.

I have been beating my head against the wall on this. I had the USB plugged into a 4-way hub. I unplugged it and plugged it directly into the iMac. Instant success!

Nonsense. The drive is brand new. It might be a firmware of course.