SourceTree doesn't run KDiff3 correctly - "Opening of these files failed"

[Jason Haines]

I installed (latest Windows versions of) SourceTree 1.6.3.0 and KDiff 0.9.98 and configured KDiff3 as the external diff tool.

When I right-click on an "Unstaged file" and run an "External Diff", KDiff3 start and reports a "File Open Error":

Opening of these files failed: - C:/tmp/Va79su_<my filename>

The directory C:\tmp\ is empty (even after I created the directory). I've tried KDiff3 and Custom command-line settings for "External Diff Tool" and get the same result.

[Balázs Szakmáry]

The answer here might help.

[Jason Haines]

Unfortunately not.