Fix joining over federation

1 files changed, 1 insertions, 0 deletions

diff --git a/synapse/storage/__init__.py b/synapse/storage/__init__.py

index 48ad4d864f..96adf20c89 100644
--- a/synapse/storage/__init__.py
+++ b/synapse/storage/__init__.py
@@ -310,6 +310,7 @@ class DataStore(RoomMemberStore, RoomStore,
                     "room_id": event.room_id,
                     "auth_id": auth_id,
                 },
+                or_ignore=True,
             )
 
         (ref_alg, ref_hash_bytes) = compute_event_reference_hash(event)