Correct field name for stripped state events when knocking. `knock_state_events` -> `knock_room_state` (#14102)

2 files changed, 9 insertions, 2 deletions

diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py
index 4dca711cd2..b220ab43fc 100644
--- a/synapse/federation/federation_client.py
+++ b/synapse/federation/federation_client.py
@@ -1294,7 +1294,7 @@ class FederationClient(FederationBase):
         return resp[1]
 
     async def send_knock(self, destinations: List[str], pdu: EventBase) -> JsonDict:
-        """Attempts to send a knock event to given a list of servers. Iterates
+        """Attempts to send a knock event to a given list of servers. Iterates
         through the list until one attempt succeeds.
 
         Doing so will cause the remote server to add the event to the graph,
diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py
index 907940e19e..28097664b4 100644
--- a/synapse/federation/federation_server.py
+++ b/synapse/federation/federation_server.py
@@ -824,7 +824,14 @@ class FederationServer(FederationBase):
                 context, self._room_prejoin_state_types
             )
         )
-        return {"knock_state_events": stripped_room_state}
+        return {
+            "knock_room_state": stripped_room_state,
+            # Since v1.37, Synapse incorrectly used "knock_state_events" for this field.
+            # Thus, we also populate a 'knock_state_events' with the same content to
+            # support old instances.
+            # See https://github.com/matrix-org/synapse/issues/14088.
+            "knock_state_events": stripped_room_state,
+        }
 
     async def _on_send_membership_event(
         self, origin: str, content: JsonDict, membership_type: str, room_id: str