cygwin error in windows 8.1 during making hex file in nios command shell for qts 14.0

Download the patch at the bottom of this page:

http://www.altera.com/education/univ/unv-index.html

Now, ignore the instructions on that page, they don't apply to 14.0

First copy

C:\altera\14.0\quartus\bin64\cygwin

To

C:\altera\14.0\quartus\bin64\cygwin.old

(To make a backup copy in case something goes wrong)

Extract the files from cygwin_patch.zip to somewhere like your desktop or downloads folder, then copy the contents of the 'bin' folder (NOT the bin64 folder!) to:

C:\altera\14.0\quartus\bin64

Merging folders and replacing any files.

The error should have gone away.