1 files changed, 12 insertions, 0 deletions
diff --git a/synapse/rest/client/v1/room.py b/synapse/rest/client/v1/room.py
index 5aef8238b8..6f31584c51 100644
--- a/synapse/rest/client/v1/room.py
+++ b/synapse/rest/client/v1/room.py
@@ -184,6 +184,12 @@ class RoomStateEventRestServlet(TransactionRestServlet):
 
         content = parse_json_object_from_request(request)
 
+        if event_type == EventTypes.Aliases:
+            # MSC2260
+            raise SynapseError(
+                400, "Cannot send m.room.aliases events via /rooms/{room_id}/state"
+            )
+
         event_dict = {
             "type": event_type,
             "content": content,
@@ -231,6 +237,12 @@ class RoomSendEventRestServlet(TransactionRestServlet):
         requester = await self.auth.get_user_by_req(request, allow_guest=True)
         content = parse_json_object_from_request(request)
 
+        if event_type == EventTypes.Aliases:
+            # MSC2260
+            raise SynapseError(
+                400, "Cannot send m.room.aliases events via /rooms/{room_id}/send"
+            )
+
         event_dict = {
             "type": event_type,
             "content": content,