diff --git a/changelog.d/4297.misc b/changelog.d/4297.misc
new file mode 100644
index 0000000000..63106e26f6
--- /dev/null
+++ b/changelog.d/4297.misc
@@ -0,0 +1 @@
+Log room_id in Unknown room errors
diff --git a/synapse/storage/state.py b/synapse/storage/state.py
index d737bd6778..a134e9b3e8 100644
--- a/synapse/storage/state.py
+++ b/synapse/storage/state.py
@@ -432,7 +432,7 @@ class StateGroupWorkerStore(EventsWorkerStore, SQLBaseStore):
         create_id = state_ids.get((EventTypes.Create, ""))
 
         if not create_id:
-            raise NotFoundError("Unknown room")
+            raise NotFoundError("Unknown room %s" % (room_id))
 
         create_event = yield self.get_event(create_id)
         defer.returnValue(create_event.content.get("room_version", "1"))