diff --git a/changelog.d/9619.misc b/changelog.d/9619.misc
new file mode 100644
index 000000000..50267bfbc
--- /dev/null
+++ b/changelog.d/9619.misc
@@ -0,0 +1 @@
+Prevent attempting to bundle aggregations for state events in /context APIs.
\ No newline at end of file
diff --git a/synapse/rest/admin/rooms.py b/synapse/rest/admin/rooms.py
index f2c42a0f3..263d8ec07 100644
--- a/synapse/rest/admin/rooms.py
+++ b/synapse/rest/admin/rooms.py
@@ -685,7 +685,10 @@ class RoomEventContextServlet(RestServlet):
             results["events_after"], time_now
         )
         results["state"] = await self._event_serializer.serialize_events(
-            results["state"], time_now
+            results["state"],
+            time_now,
+            # No need to bundle aggregations for state events
+            bundle_aggregations=False,
         )
 
         return 200, results
diff --git a/synapse/rest/client/v1/room.py b/synapse/rest/client/v1/room.py
index 9a1df30c2..5884daea6 100644
--- a/synapse/rest/client/v1/room.py
+++ b/synapse/rest/client/v1/room.py
@@ -671,7 +671,10 @@ class RoomEventContextServlet(RestServlet):
             results["events_after"], time_now
         )
         results["state"] = await self._event_serializer.serialize_events(
-            results["state"], time_now
+            results["state"],
+            time_now,
+            # No need to bundle aggregations for state events
+            bundle_aggregations=False,
         )
 
         return 200, results