extensions/models.py

@@ -675,7 +675,11 @@ class Version(CreatedModifiedMixin, TrackChangesMixin, models.Model):
     # if it isn't cached, then the save call is applied to a different, newly fetched File instance
     @cached_property
     def file(self):
-        return self.files.first()
+        files = list(self.files.all())
+        if files:
+            return files[0]
+        else:
+            return None
 
     @property
     def is_listed(self):