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SourceTree will no longer start


SourceTree on my workstation was recently updated - currently version 2.3.1.   Although I didn't explicitly update it, I know it was updated because the icon changed on my task bar.

Now, since the last reboot, when I try to start SourceTree, nothing happens.

Looking into sourcetree.log, the following is logged:   (As you can see it's getting a NullReferenceException and quitting)

What do I do?

Thanks, in advance, for any help you can lend.



( I've edited this point 3 times now to update things, and now it says SPAM??  Really?  It is NOT spam.   I need a resolution to this problem. )


ERROR [2017-09-18 20:25:41,868] [1] [SourceTree.App] [.ctor] - finish EnsureSquirrelExecutionStubIsCopied
ERROR [2017-09-18 20:25:41,968] [1] [SourceTree.App] [OnStartup] - Failed to start
System.NullReferenceException: Object reference not set to an instance of an object.
   at SourceTree.Notifications.NotificationsManager.SetOwner(NotificationDialogWindow notificationWindow)
   at SourceTree.Notifications.NotificationsManager.ShowNotificationDialog[T](NotificationDialogWindow notificationWindow, Tuple`2 customAction, VistaTaskDialogIcon icon)
   at SourceTree.Notifications.NotificationsManager.ShowNotificationDialog[T](String title, String message, Tuple`2 customAction, String cancelLabel, String suppressionSetting, Action`1 suppressionChangedAction, Object contentControl, String contentCommandLabel, Action contentAction)
   at SourceTree.Notifications.NotificationsManager.ShowNotificationDialogWithYesConfirmation(String title, String message, String details)
   at SourceTree.Configuration.WpfSpellCheckerPreFlightCheck.Run()
   at SourceTree.AppRoot.RunPreFlightChecks()
   at SourceTree.AppRoot.OnStartup(StartupEventArgs e)
   at SourceTree.App.OnStartup(StartupEventArgs e)

2 answers

1 accepted

11 votes
Answer accepted
Mike Corsaro Atlassian Team Sep 19, 2017

Hello! This is a known issue. Please navigate to the config file location (C:\Users\{USERNAME}\AppData\Local\Atlassian\SourceTree.exe_{RANDOM_GUID}\\user.config) and find the following line:

<setting name="AutomaticallyCleanUpDictionaryFiles" serializeAs="String"> 


Make sure that value is set to True

Thanks!   I added this and the problem went away.

After I added this line it worked. Thank

I had the same issue - I couldn't get SourceTree to start even after doing a full clean install.  

The "AutomaticallyCleanUpDictionaryFiles" line wasn't in my user.config.  I added it and now I can open SourceTree. 

Another +1 on this (Windows 10 Pro + ST ... had to add the line and then it worked.

I added this and the application opened again, but when I returned to the user.config file, the lines I added were removed by SourceTree again... am I going to have to keep setting this? Why is it getting cleared?

Thanks! Adding this setting solved for me (Win 10 16299.15, SourceTree 👍

Worked for me. But guys, please fix this problem. I just wasted about 1.5 hours trying to find the solution.

0 votes
Ana Retamal Atlassian Team Oct 18, 2017

Hi everyone! As an update for this topic, we have just started the progressive rollout of Sourcetree v2.3.5.0 which includes a fix for this issue. You should be prompted to upgrade sometime over the next 14 days or, alternatively, you can download the update directly from

Cheers :)


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