removed application via features / programs
deleted SourceTree and Atlasian folder from %appdata%
downloaded 2.3.1 installer
problem: application will not start. tried as admin. that did not work either.
here is a log file from the appdata/local/atlassian/sourcetree folder
ERROR [2017-09-21 16:06:01,968] [1] [SourceTree.App] [.ctor] - finish EnsureSquirrelExecutionStubIsCopied
ERROR [2017-09-21 16:06:02,104] [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)
ERROR [2017-09-21 16:06:06,954] [1] [SourceTree.App] [.ctor] - finish EnsureSquirrelExecutionStubIsCopied
ERROR [2017-09-21 16:06:07,108] [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)
ERROR [2017-09-21 16:06:12,267] [1] [SourceTree.App] [.ctor] - finish EnsureSquirrelExecutionStubIsCopied
ERROR [2017-09-21 16:06:12,409] [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)
ERROR [2017-09-21 16:06:20,309] [1] [SourceTree.App] [.ctor] - finish EnsureSquirrelExecutionStubIsCopied
ERROR [2017-09-21 16:06:20,429] [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)
ERROR [2017-09-21 16:06:35,822] [1] [SourceTree.App] [.ctor] - finish EnsureSquirrelExecutionStubIsCopied
ERROR [2017-09-21 16:06:35,957] [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)
ERROR [2017-09-21 16:23:14,469] [1] [SourceTree.App] [.ctor] - finish EnsureSquirrelExecutionStubIsCopied
ERROR [2017-09-21 16:23:14,604] [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)
ERROR [2017-09-21 16:24:36,406] [1] [SourceTree.App] [.ctor] - finish EnsureSquirrelExecutionStubIsCopied
ERROR [2017-09-21 16:24:36,521] [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)