Vimdiff failing with “Cannot read or write temp files”

Question

I\'m using Vim 7.4 on Windows 7.

I do have a custom _vimrc file, but both Vim and gVim work fine. When I try to run vimdiff .\\xxxxx .\\yyyyy, it gives the

Answer 1

I also was getting the messages

E810: Cannot read or write temp files
E97: Cannot create diffs

However my _vimrc file was fine.

The issue was that C:\Program Files\Vim\vim74 was not in the PATH environment variable, so Vim could not launch diff.exe.