diff --git a/v4.0.1/tasks-schema.json b/v4.0.1/tasks-schema.json
index f0dd500..7a46aab 100644
--- a/v4.0.1/tasks-schema.json
+++ b/v4.0.1/tasks-schema.json
@@ -1502,6 +1502,10 @@
                         "round_id": {
                             "pattern": "^([0-9]{4}-[0-9]{2}-[0-9]{2})$|^[A-Za-z0-9_]+$"
                         }
+                    },
+                    "errorMessage": {
+                        "properties": {
+                            "round_id": "must match either an ISO date format (YYYY-MM-DD) or alphanumeric characters separated by underscores."}
                     }
                 },
                 "required": [