SourceGear Support

Did you try the suggestions from the post above yours? What happens if you use it outside of Git? I did, and redirecting stderr to /dev/null did not change anything. Running diffmerge from the command line or through Git as a difftool/mergetool all result in the same error dialog. Opening DiffMerge...

When I launch DiffMerge from command line I see a pop up dialog with the following info: wxWidgets Debug Alert /build/sgdm400/Apple/intel/Release_patched/wxWidgets-3.0.0-rc1/src/common/arrstr.cpp(368): assert "nIndex < m_nCount" failed in RemoveAt(): bad index in wxArrayString::Remove Cal...

I'm having the same issue on Yosemite. Any feedback from the devs would be appreciated; for now, I'll just stick to the FileMerge that comes packaged with Xcode.