diff --git a/ChatController/ChatMainControl.xaml.cs b/ChatController/ChatMainControl.xaml.cs
index d59ed7f..ad1390e 100644
--- a/ChatController/ChatMainControl.xaml.cs
+++ b/ChatController/ChatMainControl.xaml.cs
@@ -396,7 +396,7 @@ namespace ChatController
 
             _ScrollPrueferAktivieren = false;
 
-            if(contact.HasUnreadMessages)
+            if(contact?.HasUnreadMessages ?? false)
             {
                 contact.HasUnreadMessages = false;
 
@@ -422,17 +422,17 @@ namespace ChatController
             {
                 foreach(var obj in Clientlist.Items)
                 {
-                    if(obj is ContactDependencyObject contactDependencyObject && Equals(contactDependencyObject.Contact, contact))
+                    if(obj is ContactDependencyObject contactDependencyObject && contact != null && contactDependencyObject.Contact != null && Equals(contactDependencyObject.Contact, contact))
                     {
                         Clientlist.SelectedItem = obj;
                     }
                 }
             }
 
-            _ChatMessages.Clear();
+            _ChatMessages?.Clear();
             OnPropertyChanged(nameof(_ChatMessages));
 
-            Chat.LoadChatMessagesForContactAsync(currentContact, GetFirstMessage(), chatMessages =>
+            Chat?.LoadChatMessagesForContactAsync(currentContact, GetFirstMessage(), chatMessages =>
             {
                 this.Dispatch(() =>
                 {