E810: Cannot read or write temp files E97: Cannot create diffs FIX (that worked for me): In MyDiff() of _vimrc, go to line 13 and change the two single quotes to double quotes. This allows the pattern in the IF-test to match. So change: if &sh =~ '\<cmd' (fails) To: if &sh =~ "\<cmd" (works) Or keep single quotes but escape the backslash: if &sh =~ '\\<cmd' (also works) from https://groups.google.com/forum/#!msg/vim_use/SR12FCxkQYg/aZIGO33waN0J