diff --git a/fedn/network/controller/control.py b/fedn/network/controller/control.py
index 4fcfcd734..c2b430fd5 100644
--- a/fedn/network/controller/control.py
+++ b/fedn/network/controller/control.py
@@ -129,7 +129,7 @@ def start_session(self, session_id: str, rounds: int, round_timeout: int) -> Non
 
         for combiner in self.network.get_combiners():
             combiner.set_aggregator(aggregator)
-            if session_config["server_functions"] is not None:
+            if session_config.get("server_functions", None) is not None:
                 combiner.set_server_functions(session_config["server_functions"])
 
         self.set_session_status(session_id, "Started")