SourceTree - external diff tool doesn't launch and conflicts disappear
Asked by Gilly Dekel:

Hi

I am using SourceTree with Xcode's FileMerge. This has always worked fine. Today, when I right click-\>resolve using external diff tool, I get a window for a second showing that the launch is happening, and then nothing and the conflict disappears as though resolved. This is really bad as I am unable to merge changes.

Going into preferences, I tried to change the diff tool, but I can't click on any of the values - everything seems to be locked.

Help?


Answers:
author: easymile_vramiro
body: I had the same problem, it turns out it was an Xcode problem

Run: `sudo xcode-select -s /Applications/Xcode.app/Contents/Developer`

comments: author: Andrea Ciani
body: This worked for me


author: Yogesh Randhawa
body: This worked for me


author: Alexey Shklyaev
body: Yes that worked for me, using FileMerge


author: danielmarcotte
body: I have no idea what this command is doing, but it fixed my problem. Thank you.


author: Roelof Koelewijn
body: Super! this works for me.


author: Riley Hooper
body: Worked for me running SourceTree 2.7.6 (177) and Xcode 9.4.1.


author: toni
body: Thanks, solved by run that magic command.


author: Rodrigo S_ Chavarria Rivera
body: It works great for me, perfectly


author: Becca Owens
body: Worked for me. Thank you!


author: Gabriele Trabucco
body: I came from a clean Mac Installation ... As you said I found the command line tool was not properly configured. Nice catch! Thanks


author: RichAppz
body: Worked for me! Thanks


author: kakitayuri
body: Just a note for anyone else stumbling on this page - this appears to be a Mac thing, not an iOS thing. I'm an Android dev that doesn't much use Xcode, but this was exactly what I needed. Not the first time Xcode has screwed my dev environments.


author: Rick Thomson
body: I can confirm this worked for me, though had to change path to match my beta xcode location


author: thefrosty
body: Worked for me, since I've got a clean Mac installation.


author: Jason Dahn
body: Perfect, worked for me. Thank you!


author: Joseph Razon
body: Worked for me, tnx :)


author: Tom Br?ckner
body: Same here. Thanks.


author: tigerzhang
body: Worked for me, Thank you!


author: halcyonix
body: Also worked for me. Thanks a bunch!!


author: Bal?zs Szakm?ry
body: * When the diff tool is not (correctly) configured, it behaves the way you described. (not very informative...)
* In Tools\\Options\\General, you need to enable "Allow SourceTree to modify your global config files" at the top before you can change the Diff settings.
* If you have the Diff / Merge tools set to "System default" (this is the default setting), it seems to never work.

So I think what you need to do is:

1. enable the "Allow..." option
2. change the diff tool to explicitly specify the right tool with the right cmd options

comments: author: Duarte Molha
body: This is still not working for me. THe external diff tool does not launch!


author: Trung Duy Van
body: Thanks. It work perfect


author: hussien_khayoon
body: In Mac, I had to go to SourceTree/Preferences/General


author: Lynna Landstreet
body: This did not work for me. That option is checked, Diff/Merge tool is set explicitly to FileMerge (which is what it was using before it abruptly stopped working), and as recommended in another answer here, I have it set to Embedded Git rather than System Git, but none of that helped at all.  

It used to work fine, and then suddenly stopped working a while back, without my having changed any configuration options whatsoever. I'm guessing it was when SourceTree automatically updated itself or something... But anyway, none of the answers in this post have helped for me.


author: Jeff McKnight
body: Tested with Sourcetree v2.7.1 and DiffMerge v4.2.1 (with command line tools) on MacOS v10.13.3:

1. Open Sourcetree prefs and select \`Diff\` tab

2. Set \`Visual Diff Tool\` menu to \`Custom\`

3. Set \`Diff command\` field to: /usr/local/bin/diffmerge

4. Set \`Arguments\` field to: $LOCAL $REMOTE

5. Close prefs, select External Diff (or cmd-D) and observe DiffMerg launches.

More info here:

<https://sourcegear.com/diffmerge/webhelp/sec__git__mac.html>

comments: author: t_anjan
body: You can do the same for "Merge Command" too.

Merge Command:

```
/usr/local/bin/diffmerge
```

Arguments:

```
--merge --result="$MERGED" "$LOCAL" "$BASE" "$REMOTE"
```


author: Jeff McKnight
body: Works!


author: jeremy_stafford
body: None of these worked for me either. Using latest SourceTree with Beyond compare. It doesn't happen on every file. I don't know what the common factor is on the files that it does happen with.

EDIT:

So it turns out the two files I was just trying to merge, the difference was that the file was no longer existent on the remote server. Rather than do something about the merge to show it was deleted, it just hung forever.

comments: author: jorge granados
body: This was the right answer. Files no longer exist on remote server.


author: crobicha
body: Was the solution for me as well. Can't believe there wasn't a simple error message or something, I spent a lot of time trying all of the other solutions, changing settings, etc


author: Matt Brand
body: This was what was happening for me. No diff = nothing happens.


author: Joshua Wojcik
body: I found changing to the Embedded Git rather than System Git fixed the problem.

comments: author: sean bzd
body: this resolved my issue as well


author: altaf-CosiGames
body: this resolved my issue as well. I had tried with DiffMerge \& Beyond Compare. Switching to System Git fixed it for me


author: Thomas Luong
body: This resolved my Issue.


author: Jeff Sorrentino
body: As a workaround I changed the name of my external diff app from

**/Applications/DiffMerge**

to

**/Applications/_DiffMerge**

Thus my diff command becomes

```
/Applications/_DiffMerge.app/Contents/MacOS/DiffMerge
```

with arguments

```
"$LOCAL" "$REMOTE"?
```

comments: author: Jonathan Oliver
body: Even when I edited the .gitconfig diff tool path and fixed it by removing portion of the path, each time I'd restart DiffMerge, it would reappear.

```
/Applications/DiffMerge.app/Contents/MacOS/DiffMerge/Contents/MacOS/DiffMerge
```

So, here's the workaround.

1. Symlink DiffMerge to another location (so it's not auto-detected as DiffMerge)

```
ln -s /Application/DiffMerge.app /Applications/_DiffMerge.app
```

2. Then select a custom diff and merge tool arguments.

Diff command arguments:

```
--nosplash "$LOCAL" "$REMOTE"
```

Merge tool arguments:

```
--merge --result="$MERGED" "$LOCAL" "$BASE" "$REMOTE"
```

![Screen Shot 2018-11-07 at 7.03.22 PM.png](https://community.atlassian.com/t5/image/serverpage/image-id/37038iAF652233336F71E8/image-size/large?v=v2&px=999 "Screen Shot 2018-11-07 at 7.03.22 PM.png")

After this, SourceTree will no longer mangle the path at startup because it doesn't think it's DiffMerge anymore.


author: voidpointer2
body: Works for me.

Just wanted to note:

```
ln -s /Application/DiffMerge.app /Applications/_DiffMerge.app
```

Should be:

```
ln -s /Applications/DiffMerge.app /Applications/_DiffMerge.app
```

I can't believe this trivial bug has not been fixed yet.


author: milennium9
body: I had same problem.

1. open your git global config file.
2. check syntax error.

then I can fix the problem.

I think this is sourcetree bug.

comments: author: KevinCondon
body: Yup, the path to diffmerge had part of it duplicated. Fixing it did the trick. Thanks!


author: seanchon
body: Same problem here. I had to accept the user agreement in the terminal before it would launch from SourceTree. Running 'sudo opendiff' worked for me.

comments: author: Val Gorbatyuk
body: This was it for me


author: Patrick Galbraith
body: I had this issue on Windows. The problem was caused by an upgrade that inserted backslashes "\\" into the merge command arguments.

```
\"$LOCAL\" \"$REMOTE\"
```

Should be changed to:

```
"$LOCAL" "$REMOTE"
```

comments: author: ewbachtal
body: Ooooooh! A winner! It's been months since external diff worked, I'd been through all the suggestions, saw those slashes but figured it was some sort of necessary string escaping and never considered that might be the cause. Thank you!


author: Becca Owens
body: I was experiencing this as well, and discovered I'd had a derp moment. The file I was trying to merge had been deleted, therefore there was nothing to merge. :\\


author: Femi Ojemuyiwa
body: Nothing above works anymore for diffmerge. Is there going to be a fix in next release or shall we just try any and every solution?

comments: author: Jonathan Oliver
body: I just posted a reply above that works as off SourceTree v3.0


author: GarethJ
body: The fix is yet to arrove but there's a workaround at <https://jira.atlassian.com/browse/SRCTREE-2211>


author: Brad Curran
body: If none of these things work, try running \`opendiff\` in the Terminal.

It there's an error like below you need to do one of two things:

* Install XCode
* Install another diff program

As of writing SourceTree supports the following programs:

* Araxis Merge
* Beyond Compare
* BBEdit
* DiffFork
* DiffMerge
* Changes
* FileMerge
* Kaleidoscope
* KDiff3
* P4Merge
* TextWrangler


author: greenboim
body: Hi Yair,

I had the same problem.

As Balazs said, it was because the "System default" was selected for the merge tool. Download a tool and set it as your resolving tool.