diff --git a/ChatController/ChatMainControl.xaml.cs b/ChatController/ChatMainControl.xaml.cs
index 01eab05..419c663 100644
--- a/ChatController/ChatMainControl.xaml.cs
+++ b/ChatController/ChatMainControl.xaml.cs
@@ -906,66 +906,74 @@ namespace ChatController
 
                         this.Dispatch(() =>
                         {
-                            foreach (var contactDependencyObject in _ContactList)
+                            try
                             {
-                                foreach (var newContact in updatedContacts)
+                                foreach (var contactDependencyObject in _ContactList)
                                 {
-                                    if (contactDependencyObject.Contact.GroupId == newContact.GroupId)
+                                    foreach (var newContact in updatedContacts)
                                     {
-                                        // ReceivedMessage kann null sein!
-                                        if (!(contactDependencyObject.Contact.ReceivedMessage is null) && !contactDependencyObject.Contact.ReceivedMessage.Id.Equals(newContact.ReceivedMessage?.Id))
+                                        if (contactDependencyObject.Contact.GroupId == newContact.GroupId)
                                         {
-                                            contactDependencyObject.Contact.ReceivedMessage = newContact.ReceivedMessage;
-                                            contactDependencyObject.Contact.TimeStamp = newContact.TimeStamp;
-
-                                            Contact selectedContact = null;
-
-                                            if(Clientlist.SelectedItem is ContactDependencyObject selectedContactDependencyObject)
+                                            // ReceivedMessage kann null sein!
+                                            if (!(contactDependencyObject.Contact.ReceivedMessage is null) && !contactDependencyObject.Contact.ReceivedMessage.Id.Equals(newContact.ReceivedMessage?.Id))
                                             {
-                                                selectedContact = selectedContactDependencyObject.Contact;
-                                            }
+                                                contactDependencyObject.Contact.ReceivedMessage = newContact.ReceivedMessage;
+                                                contactDependencyObject.Contact.TimeStamp = newContact.TimeStamp;
 
-                                            // Angemeldeter Benutzer
-                                            var userOid = Chat.ChatDaten.LoggedInUser.Response.User.Oid;
+                                                Contact selectedContact = null;
 
-                                            var senderId = contactDependencyObject.Contact.ReceivedMessage?.UserId;
-                                            var receiverId = userOid;
-                                            var receiverGroupId = newContact.GroupId;
-                                            var selectedGroupId = selectedContact?.GroupId;
-
-                                            if (senderId != receiverId && (_IsInBackground || receiverGroupId != selectedGroupId))
-                                            {
-                                                if (!(ContainingWindow is null))
+                                                if(Clientlist.SelectedItem is ContactDependencyObject selectedContactDependencyObject)
                                                 {
-                                                    ContainingWindow.Icon = Utils.ConvertIconToImageSource(Resource.oC_favico_NewMessage);
+                                                    selectedContact = selectedContactDependencyObject.Contact;
                                                 }
 
-                                                ShowNotification(newContact.Name, newContact.ReceivedMessage, newContact.GroupId);
-                                            }
+                                                // Angemeldeter Benutzer
+                                                var userOid = Chat.ChatDaten.LoggedInUser.Response.User.Oid;
 
-                                            // Wenn der momentan ausgewählte Kontakt der aktuelle Kontakt in der Schleife ist, werden die Nachrichten nicht als ungelesen angezeigt, sonst schon.
-                                            if (!(CurrentContact is null) && newContact.GroupId == CurrentContact.GroupId)
-                                            {
-                                                contactDependencyObject.Contact.HasUnreadMessages = false;
-                                            }
-                                            else
-                                            {
-                                                contactDependencyObject.Contact.HasUnreadMessages = true;
-                                                contactDependencyObject.Contact.IsNewMessage = true;
+                                                var senderId = contactDependencyObject.Contact.ReceivedMessage?.UserId;
+                                                var receiverId = userOid;
+                                                var receiverGroupId = newContact.GroupId;
+                                                var selectedGroupId = selectedContact?.GroupId;
+
+                                                if (senderId != receiverId && (_IsInBackground || receiverGroupId != selectedGroupId))
+                                                {
+                                                    if (!(ContainingWindow is null))
+                                                    {
+                                                        ContainingWindow.Icon = Utils.ConvertIconToImageSource(Resource.oC_favico_NewMessage);
+                                                    }
+
+                                                    ShowNotification(newContact.Name, newContact.ReceivedMessage, newContact.GroupId);
+                                                }
+
+                                                // Wenn der momentan ausgewählte Kontakt der aktuelle Kontakt in der Schleife ist, werden die Nachrichten nicht als ungelesen angezeigt, sonst schon.
+                                                if (!(CurrentContact is null) && newContact.GroupId == CurrentContact.GroupId)
+                                                {
+                                                    contactDependencyObject.Contact.HasUnreadMessages = false;
+                                                }
+                                                else
+                                                {
+                                                    contactDependencyObject.Contact.HasUnreadMessages = true;
+                                                    contactDependencyObject.Contact.IsNewMessage = true;
+                                                }
                                             }
                                         }
                                     }
+
+                                    if (!updatedContacts.Contains(contactDependencyObject.Contact))
+                                    {
+                                        _ContactList.ToList().Remove(contactDependencyObject);
+                                    }
                                 }
 
-                                if (!updatedContacts.Contains(contactDependencyObject.Contact))
-                                {
-                                    _ContactList.ToList().Remove(contactDependencyObject);
-                                }
+                                ContactList.Sort((x, y) => DateTime.Compare(y.Contact.TimeStamp, x.Contact.TimeStamp));
+                                OnPropertyChanged(nameof(ChatMessages));
+                                OnPropertyChanged(nameof(ContactList));
+                            }
+                            catch(Exception exception)
+                            {
+                                Console.WriteLine(exception);
+                                throw;
                             }
-
-                            ContactList.Sort((x, y) => DateTime.Compare(y.Contact.TimeStamp, x.Contact.TimeStamp));
-                            OnPropertyChanged(nameof(ChatMessages));
-                            OnPropertyChanged(nameof(ContactList));
                         });
                     });
                 }