Update .gitconfig file located in C:\Users\USERNAME directory with the following data.
[diff]
tool = meld
[difftool]
prompt = false
[difftool "meld"]
path = C:\\Program Files (x86)\\Meld\\Meld.exe
cmd = 'C:\\Program Files (x86)\\Meld\\Meld.exe' "$REMOTE" "$LOCAL"
[merge]
tool = meld
[mergetool]
prompt = false
[mergetool "meld"]
path = C:\\Program Files (x86)\\Meld\\Meld.exe
cmd = 'C:\\Program Files (x86)\\Meld\\Meld.exe' "$REMOTE" "$MERGED" "$LOCAL" --output "$MERGED"If you encounter this error under Windows /mingw64/libexec/git-core/git-mergetool--lib: line 124: c:/Program Files (x86)/Meld/Meld.exe: Permission denied uncheck 'Run as Administrator' in Properties -> Compatibility of Meld.exe.