1 files changed, 10 insertions, 0 deletions
diff --git a/synapse/rest/client/account_data.py b/synapse/rest/client/account_data.py
index 6d13be1a7c..a5779db0ed 100644
--- a/synapse/rest/client/account_data.py
+++ b/synapse/rest/client/account_data.py
@@ -83,6 +83,11 @@ class AccountDataServlet(RestServlet):
         if event is None:
             raise NotFoundError("Account data not found")
 
+        # If experimental support for MSC3391 is enabled, then this endpoint should
+        # return a 404 if the content for an account data type is an empty dict.
+        if self._hs.config.experimental.msc3391_enabled and event == {}:
+            raise NotFoundError("Account data not found")
+
         return 200, event
 
 
@@ -209,6 +214,11 @@ class RoomAccountDataServlet(RestServlet):
         if event is None:
             raise NotFoundError("Room account data not found")
 
+        # If experimental support for MSC3391 is enabled, then this endpoint should
+        # return a 404 if the content for an account data type is an empty dict.
+        if self._hs.config.experimental.msc3391_enabled and event == {}:
+            raise NotFoundError("Room account data not found")
+
         return 200, event