Keith W. Blackwell

Looks like an exact duplicate of https://sourceforge.net/p/gnuplot/bugs/2224/

I just saw the issue with the gp545-win64-mingw.exe while upgrading from 5.2.something. First guess: the CMD shell is being used to interpret the execute command (or something like it) and yet the path to the executable contains an unescaped space; but that doesn't sound right since the message mentions the entire path! So maybe the execution is providing a directory to cd to first, and that one is improperly formed. I dunno. It's just the installer itself doing this, and I've probably never checked...