diff --git a/candig_federation/heartbeat.py b/candig_federation/heartbeat.py
index 6130981..9e8971d 100644
--- a/candig_federation/heartbeat.py
+++ b/candig_federation/heartbeat.py
@@ -7,6 +7,8 @@
 
 def check_pulse():
     servers = get_registered_servers()
+    if servers is None:
+        return
     if len(servers) == 0:
         return
     # Determine which sites we have access to
diff --git a/candig_federation/operations.py b/candig_federation/operations.py
index e9d9490..2996102 100644
--- a/candig_federation/operations.py
+++ b/candig_federation/operations.py
@@ -115,7 +115,11 @@ def list_services():
     """
     :return: Dictionary of registered services.
     """
-    return list(get_registered_services().values()), 200
+    services = get_registered_services()
+    if services is not None:
+        return list(services.values()), 200
+    logger.debug(f"Couldn't list services", request)
+    return {"message": "Couldn't list services"}, 500
 
 
 @app.route('/services/<path:service_id>')