2 files changed, 4 insertions, 1 deletions
diff --git a/synapse/events/snapshot.py b/synapse/events/snapshot.py
index ca15ec09ae..e0cbacc19c 100644
--- a/synapse/events/snapshot.py
+++ b/synapse/events/snapshot.py
@@ -58,6 +58,7 @@ class EventCache(object):
 
 class EventContext(object):
 
-    def __init__(self, current_state, auth_events):
+    def __init__(self, current_state=None, auth_events=None):
         self.current_state = current_state
         self.auth_events = auth_events
+        self.state_group = None
diff --git a/synapse/events/utils.py b/synapse/events/utils.py
index 1b05ee0a95..485f075406 100644
--- a/synapse/events/utils.py
+++ b/synapse/events/utils.py
@@ -95,4 +95,6 @@ def serialize_event(hs, e):
         d["unsigned"]["age"] = now - d["unsigned"]["age_ts"]
         del d["unsigned"]["age_ts"]
 
+    d["user_id"] = d.pop("sender", None)
+
     return d
\ No newline at end of file