Note: This post is 8 years old. Some information may no longer be correct or even relevant. Please, keep this in mind while reading.
I got this error message when I wanted to use dd to copy a raw image to a MicroSD card. You will see this message if you have unmounted the card with a file manager like Nautilus. I guess it unmounts not fully, or in a special way.
The fix is easy:
Unmount the card via the terminal:
umount /dev/sdd1The dd command will work now.
Another variant of this error can be seen when using bmaptool :
bmaptool: ERROR: cannot open destination file '/dev/sdd': [Errno 123] No medium found: '/dev/sdd'