1 files changed, 5 insertions, 0 deletions
diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py
index 15a9a88302..f185b6c1f9 100644
--- a/synapse/federation/federation_client.py
+++ b/synapse/federation/federation_client.py
@@ -1157,6 +1157,11 @@ class FederationClient(FederationBase):
                     "members_omitted was set, but no servers were listed in the room"
                 )
 
+            if response.members_omitted and not partial_state:
+                raise InvalidResponseError(
+                    "members_omitted was set, but we asked for full state"
+                )
+
             return SendJoinResult(
                 event=event,
                 state=signed_state,