It's not the same without you

Join the community to find out what other Atlassian users are discussing, debating and creating.

Atlassian Community Hero Image Collage

Cannot Launch KDiff3 External Merge Tool from Sourcetree

I am not sure what the issue is all of a sudden.  It was working a few times, then all of a sudden it no longer will work.  It says it is launching the tool but then nothing happens.  I am unable to effectively resolve conflicts and need this to work properly.  


I updated to 2.3.5 and it still isn't working.  Has anyone else solved this issue?

6 answers

1 accepted

0 votes
Answer accepted

To anyone else having this problem do yourself a favor and download GitKraken.  Problem solved.  They apparently know how to use GitMerge and GitDiff properly.

This is not a real solution to the issue at hand. It is just using a different product.

Like 1 person likes this

This is straight up Bullcrap from a "professional" software developer to release something with such a buggy MUST HAVE feature.  How the hell can you release a product that for half the people there is no way to open an external merge/diff tool because sourcetree screws something up that leaves you attempting to go through 50 different posts to try and fix, STILL unsuccessfully I might add...


This is completely unacceptable.  I'm sorry but until Atlassian gets their head out of their ass and fixes this bug that has been in countless versions, including the latest one, I'm done using it.    I've spent 5 hours trying to resolve it, I don't have anymore time to play "find a workaround for my broken features".

1 vote

I use KDiff3 daily and its working for me. Can you provide some more details so we can try and work out the differences?

Can you check the git config settings, does it contain:

mergetool.sourcetree.cmd='C:/Program Files/KDiff3/kdiff3.exe' "$BASE" "$LOCAL" "$REMOTE" -o "$MERGED"

Sourcetree uses that setting by running

 git mergetool -y --tool=Sourcetree {filename}

Does that work from your command line?

you can try the diff equivalent as well 


git difftool -y tool=Sourcetree {oldcommithash} -- {filename}

Like 1 person likes this

In my case there's a tweak to this issue: I have a merge with a number of conflicts to resolve. I can resolve 1 conflict using kdiff3 (the KDiff3 commands configured as suggested by Joshua Brown). After this one conflict is resolved, I can't resolve any other - KDiff3 doesn't launch, as described above.


KDiff will not  trigger if, for example, the file in conflict has been deleted in one side of the merge or I've also seen cases where Sourcetree/Git appears to report a file in conflict but without any changes, possibly just whitespace? In this case KDiff will not trigger either.

We are aware of some of these annoying edge cases and plan to improve them in the future.

@Michael Minns A file being deleted on one side of the merge is considered an edge case? Took me forever to figure out that this is why KDiff didn't open. But now that I know I'll be on the lookout for it. Thanks.

Yesterday it wasn't working for me. Today, it magically is. Here are the contents of my .gitconfig file.


[difftool "sourcetree"]
cmd = 'C:/kdiff3/kdiff3.exe' \"$LOCAL\" \"$REMOTE\"
[mergetool "sourcetree"]
cmd = 'C:/kdiff3/kdiff3.exe' \"$BASE\" \"$LOCAL\" \"$REMOTE\" -o \"$MERGED\"

Your answer helped me because the mergetool setting wasn't in my .gitconfig file.  Putting it in there manually did not help, but it did make me take a 2nd look at the settings in the sourcetree UI.   I did not have the mergetool configured correctly.

This helped me too as I am a windows sourcetree user.  

Another problem I had was in the sourcetree options.  Under the "Diff" tab options there are 2 settings, one for "External Diff Tool" and one for "Merge Tool".  I assumed I had to set the "External Diff Tool" because it had the word "External" in it, but it was actually the "Merge Tool" that I had to set in order for it to work.  This should be called "External Merge Tool".  -_-

0 votes

I was having the same problem.  There are two settings in sourcetree in the Tools->options menu under the Diff tab where you need to set it to Kdiff3: the diff tool and the merge tool.  Ensure that both of them are configured to used Kdiff3.   I failed to notice that my merge tool settings were set to "System Default".   As soon as I fixed this, everything worked normally.

Suggest an answer

Log in or Sign up to answer
This widget could not be displayed.
This widget could not be displayed.
Community showcase
Posted Jan 17, 2019 in Sourcetree

[dev team] Sourcetree for Windows 2019 Preview - Dark Theme

Hi folks, While the full post is over on our blog I'd like to share the dark theme we've got planned for 2019 here directly as well to keep the discussion going.  The ...

1,336 views 12 14
Join discussion

Atlassian User Groups

Connect with like-minded Atlassian users at free events near you!

Find a group

Connect with like-minded Atlassian users at free events near you!

Find my local user group

Unfortunately there are no AUG chapters near you at the moment.

Start an AUG

You're one step closer to meeting fellow Atlassian users at your local meet up. Learn more about AUGs

Groups near you