Hi!

We have recently discovered a new error in our logs:

2024-04-11 14:14:08.974 [Error] System.InvalidOperationException: Operations that change non-concurrent collections must have exclusive access. A concurrent update was performed on this collection and corrupted its state. The collection's state is no longer correct.
   at System.Collections.Generic.Dictionary`2.TryInsert(TKey key, TValue value, InsertionBehavior behavior)
   at System.Collections.Generic.Dictionary`2.set_Item(TKey key, TValue value)
   at EPiServer.Data.Providers.Internal.SqlDatabaseExecutor..ctor(DbProviderFactory dbProviderFactory, ContextCache contextCache, ConnectionStringOptions connectionStringSettings, Int32 retries, TimeSpan retryDelay, TimeSpan databaseQueryTimeout)
   at EPiServer.Data.Providers.Internal.SqlDatabaseExecutorFactory.Create(ConnectionStringOptions connectionStringOption)
   at EPiServer.Data.Providers.Internal.SqlDatabaseDelegatorFactory.EPiServer.Data.Internal.IAsyncDatabaseExecutorFactory.CreateDefaultHandler()
   at ResolveService(ILEmitResolverBuilderRuntimeContext, ServiceProviderEngineScope)
   at Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(Type serviceType, ServiceProviderEngineScope serviceProviderEngineScope)
   at EPiServer.Data.DataInitialization.<>c__DisplayClass6_1.<ConfigureContainer>b__8()
   at EPiServer.DataAccess.Internal.NotificationSubscriptionDB.ClearSubscriptionAsync(Uri subscriptionKey)
   at EPiServer.Notification.Internal.DefaultSubscriptionService.ClearSubscriptionAsync(Uri subscriptionKey)
   at EPiServer.Cms.Shell.UI.Rest.Projects.Notifications.Internal.ProjectMessageNotifier.UnsubscribeFromAllActivitiesFromPublishedVersion(ContentReference contentLink)
   at EPiServer.Cms.Shell.UI.Rest.Projects.Notifications.Internal.ProjectMessageNotifier.ActivityCreated(Object sender, ActivityCreatedEventArgs e)

Is this something that someone else have seen?
What is the action that has caused this? The stacktrace does not indicate a scheduled job, so is it a user action?

Best regards
Johan