Sourcetree only runs once after fresh install

[Wesley Nash]

I had a strange issue start yesterday where Sourcetree would not run. I updated from 3.3.8 to the latest version, 3.4.8, and the app ran after installation. However, closing the app and trying to reopen caused the same issue. Uninstalling and reinstalling several times resulted in the same behavior: the app would run once after a fresh install, but would not reopen after being closed. Restarting my PC had no effect.

In Task Manager, two Sourcetree processes appear under Background Processes after running the executable (%localappdata%/Sourcetree/SourceTree.exe). One is appended with (32 bit) and disappears after a few seconds, but the other remains until it is manually killed. Running the executable multiple times results in multiple processes running concurrently.

Removing all Sourcetree registry keys had no effect. Windows Event Viewer does not have any logs relating to Sourcetree. The following is the content of %localappdata%/Atlassian/SourceTree/sourcetree.log:

2022-03-10T16:41:37: LogHost: Initializing to normal mode
ERROR [2022-03-10 16:42:42,440] [1] [SourceTree.Notifications.NotificationsManager] [Log] - Unable to set owner as parent is not visible or non-existent
ERROR [2022-03-10 16:42:49,710] [21] [SourceTree.Analytics.Emau.EMauSubmissionService] [Log] - Unable to generate batch, return null
System.NotSupportedException: This type of CollectionView does not support changes to its SourceCollection from a thread different from the Dispatcher thread.
at System.Windows.Data.CollectionView.OnCollectionChanged(Object sender, NotifyCollectionChangedEventArgs args)
at System.Collections.ObjectModel.ReadOnlyObservableCollection`1.OnCollectionChanged(NotifyCollectionChangedEventArgs args)
at System.Collections.ObjectModel.ObservableCollection`1.OnCollectionChanged(NotifyCollectionChangedEventArgs e)
at System.Collections.ObjectModel.ObservableCollection`1.ClearItems()
at DynamicData.ListEx.Clone[T](IList`1 source, Change`1 item, IEqualityComparer`1 equalityComparer) in d:\a\1\s\src\DynamicData\List\ListEx.cs:line 112
at DynamicData.ListEx.Clone[T](IList`1 source, IChangeSet`1 changes, IEqualityComparer`1 equalityComparer) in d:\a\1\s\src\DynamicData\List\ListEx.cs:line 76
at DynamicData.Binding.ObservableCollectionAdaptor`1.Adapt(IChangeSet`1 changes) in d:\a\1\s\src\DynamicData\Binding\ObservableCollectionAdaptor.cs:line 56
at DynamicData.ObservableListEx.<>c__DisplayClass21_0`1.<Adapt>b__1(IChangeSet`1 changes) in d:\a\1\s\src\DynamicData\List\ObservableListEx.cs:line 586
at System.Reactive.Linq.ObservableImpl.Select`2.Selector._.OnNext(TSource value) in D:\a\1\s\Rx.NET\Source\src\System.Reactive\Linq\Observable\Select.cs:line 39
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Reactive.Stubs.<>c.<.cctor>b__2_1(Exception ex) in D:\a\1\s\Rx.NET\Source\src\System.Reactive\Internal\Stubs.cs:line 16
at System.Reactive.ObserverBase`1.OnError(Exception error) in D:\a\1\s\Rx.NET\Source\src\System.Reactive\ObserverBase.cs:line 61
at System.Reactive.AutoDetachObserver`1.OnErrorCore(Exception exception) in D:\a\1\s\Rx.NET\Source\src\System.Reactive\Internal\AutoDetachObserver.cs:line 77
at System.Reactive.ObserverBase`1.OnError(Exception error) in D:\a\1\s\Rx.NET\Source\src\System.Reactive\ObserverBase.cs:line 61
at System.Reactive.Sink`1.ForwardOnError(Exception error) in D:\a\1\s\Rx.NET\Source\src\System.Reactive\Internal\Sink.cs:line 61
at System.Reactive.Linq.ObservableImpl.Select`2.Selector._.OnNext(TSource value) in D:\a\1\s\Rx.NET\Source\src\System.Reactive\Linq\Observable\Select.cs:line 41
at System.Reactive.Concurrency.Synchronize`1._.OnNext(TSource value) in D:\a\1\s\Rx.NET\Source\src\System.Reactive\Concurrency\Synchronization.Synchronize.cs:line 42
at System.Reactive.AutoDetachObserver`1.OnNextCore(T value) in D:\a\1\s\Rx.NET\Source\src\System.Reactive\Internal\AutoDetachObserver.cs:line 62
at System.Reactive.ObserverBase`1.OnNext(T value) in D:\a\1\s\Rx.NET\Source\src\System.Reactive\ObserverBase.cs:line 36
at System.Reactive.Subjects.Subject`1.OnNext(T value) in D:\a\1\s\Rx.NET\Source\src\System.Reactive\Subjects\Subject.cs:line 148
at DynamicData.SourceList`1.InvokeNext(IChangeSet`1 changes) in d:\a\1\s\src\DynamicData\List\SourceList.cs:line 120
at DynamicData.SourceList`1.Edit(Action`1 updateAction) in d:\a\1\s\src\DynamicData\List\SourceList.cs:line 93
at SourceTree.ViewModel.Hosted.HostedProjectsViewModel.LoadAccounts()
at SourceTree.ViewModel.Hosted.HostedProjectsViewModel.AccountManager_OnAccountsUpdated(Object sender, EventArgs e)
at System.EventHandler.Invoke(Object sender, EventArgs e)
at SourceTree.Accounts.AccountManager.RemoveHostedAccount(IAccount account)
at SourceTree.Accounts.AccountManager.ReplaceHostedAccount(IAccount oldAccount, IAccount newAccount)
at SourceTree.Analytics.BaseAnalyticsService.get_UserId()
at SourceTree.Analytics.Emau.EMauSubmissionService.GetAasBatch()
ERROR [2022-03-10 16:52:13,113] [1] [Sourcetree.Installer.Squirrel.Utils.UpdateHelper] [Log] - Couldn't read staging user ID
ERROR [2022-03-10 16:52:13,118] [1] [Sourcetree.Installer.Squirrel.Utils.UpdateHelper] [Log] - Couldn't read staging user ID