Cant format this External Drive - FIXED

[Microman]

Disk Util says that its fine with first aid. When I choose to erase, it unmount, and then gives me this error:

It's a 2.5" drive that is mounted in a data to usb plugin thingy from another drive.

Mounts fine, and can read files from it.. Just cant erase.

[Tiangou]

Does the same error occur when you use "Show all devices" and erase it from the device-level instead of the volume-level?

[Microman]

Tiangou, that worked, thanks... very much!!

[rz]

I tried reformatting a PC-formatted drive just today under Sierra. Actually tried two different drives, got same error. Fired up my MacBook Pro which runs El Capitan and it worked no problem. Thanks Apple.