diff --git a/biothings/web/query/formatter.py b/biothings/web/query/formatter.py
index 2daa98aa4..04c0e6593 100644
--- a/biothings/web/query/formatter.py
+++ b/biothings/web/query/formatter.py
@@ -83,6 +83,8 @@ def __init__(self, *args, **kwargs):
             super().__init__(*args, **kwargs)
             # make sure the document is coming from
             # elasticsearch at initialization time
+            if "hits" not in self.data:
+                logger.error(f"Error loading elasticsearch result. {self.data}")
             assert "hits" in self.data
             assert "total" in self.data["hits"]
             assert "hits" in self.data["hits"]