1 files changed, 4 insertions, 1 deletions
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index c3adbc6c95..0886607023 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -575,8 +575,11 @@ class EventCreationHandler(object):
             return
 
         consent_uri = self._consent_uri_builder.build_user_consent_uri(user_id)
+        msg = self.config.block_events_without_consent_error % {
+            'consent_uri': consent_uri,
+        }
         raise ConsentNotGivenError(
-            msg=self.config.block_events_without_consent_error,
+            msg=msg,
             consent_uri=consent_uri,
         )