diff --git a/multi_user/bl_types/bl_file.py b/multi_user/bl_types/bl_file.py
index 6b07c43..f05ee18 100644
--- a/multi_user/bl_types/bl_file.py
+++ b/multi_user/bl_types/bl_file.py
@@ -63,6 +63,10 @@ class BlFile(ReplicatedDatablock):
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.instance = kwargs.get('instance', None)
+        
+        if self.instance and not self.instance.exists():
+            raise FileNotFoundError(self.instance)
+   
         self.preferences = utils.get_preferences()
         self.diff_method = DIFF_BINARY
 
diff --git a/multi_user/operators.py b/multi_user/operators.py
index 7353823..2cf41bc 100644
--- a/multi_user/operators.py
+++ b/multi_user/operators.py
@@ -139,11 +139,11 @@ class SessionStartOperator(bpy.types.Operator):
 
             runtime_settings.is_host = True
             runtime_settings.internet_ip = environment.get_ip()
-
-            for scene in bpy.data.scenes:
-                client.add(scene)
-
+            
             try:
+                for scene in bpy.data.scenes:
+                    client.add(scene)
+
                 client.host(
                     id=settings.username,
                     port=settings.port,