1 files changed, 8 insertions, 0 deletions
diff --git a/synapse/config/server.py b/synapse/config/server.py
index 0f90302c95..b3a9e50752 100644
--- a/synapse/config/server.py
+++ b/synapse/config/server.py
@@ -680,6 +680,14 @@ class ServerConfig(Config):
             config.get("use_account_validity_in_account_status") or False
         )
 
+        # This is a temporary option that enables fully using the new
+        # `device_lists_changes_in_room` without the backwards compat code. This
+        # is primarily for testing. If enabled the server should *not* be
+        # downgraded, as it may lead to missing device list updates.
+        self.use_new_device_lists_changes_in_room = (
+            config.get("use_new_device_lists_changes_in_room") or False
+        )
+
         self.rooms_to_exclude_from_sync: List[str] = (
             config.get("exclude_rooms_from_sync") or []
         )