1 files changed, 22 insertions, 9 deletions
diff --git a/synapse/handlers/room_summary.py b/synapse/handlers/room_summary.py
index 906985c754..4bc9c73e6e 100644
--- a/synapse/handlers/room_summary.py
+++ b/synapse/handlers/room_summary.py
@@ -28,7 +28,14 @@ from synapse.api.constants import (
     Membership,
     RoomTypes,
 )
-from synapse.api.errors import AuthError, Codes, NotFoundError, StoreError, SynapseError
+from synapse.api.errors import (
+    AuthError,
+    Codes,
+    NotFoundError,
+    StoreError,
+    SynapseError,
+    UnsupportedRoomVersionError,
+)
 from synapse.events import EventBase
 from synapse.events.utils import format_event_for_client_v2
 from synapse.types import JsonDict
@@ -814,7 +821,12 @@ class RoomSummaryHandler:
             logger.info("room %s is unknown, omitting from summary", room_id)
             return False
 
-        room_version = await self._store.get_room_version(room_id)
+        try:
+            room_version = await self._store.get_room_version(room_id)
+        except UnsupportedRoomVersionError:
+            # If a room with an unsupported room version is encountered, ignore
+            # it to avoid breaking the entire summary response.
+            return False
 
         # Include the room if it has join rules of public or knock.
         join_rules_event_id = state_ids.get((EventTypes.JoinRules, ""))
@@ -1139,25 +1151,26 @@ def _is_suggested_child_event(edge_event: EventBase) -> bool:
 _INVALID_ORDER_CHARS_RE = re.compile(r"[^\x20-\x7E]")
 
 
-def _child_events_comparison_key(child: EventBase) -> Tuple[bool, Optional[str], str]:
+def _child_events_comparison_key(
+    child: EventBase,
+) -> Tuple[bool, Optional[str], int, str]:
     """
     Generate a value for comparing two child events for ordering.
 
-    The rules for ordering are supposed to be:
+    The rules for ordering are:
 
     1. The 'order' key, if it is valid.
-    2. The 'origin_server_ts' of the 'm.room.create' event.
+    2. The 'origin_server_ts' of the 'm.space.child' event.
     3. The 'room_id'.
 
-    But we skip step 2 since we may not have any state from the room.
-
     Args:
         child: The event for generating a comparison key.
 
     Returns:
         The comparison key as a tuple of:
             False if the ordering is valid.
-            The ordering field.
+            The 'order' field or None if it is not given or invalid.
+            The 'origin_server_ts' field.
             The room ID.
     """
     order = child.content.get("order")
@@ -1168,4 +1181,4 @@ def _child_events_comparison_key(child: EventBase) -> Tuple[bool, Optional[str],
         order = None
 
     # Items without an order come last.
-    return (order is None, order, child.room_id)
+    return (order is None, order, child.origin_server_ts, child.room_id)