diff --git a/lib/static/hearty_rabbit.js b/lib/static/hearty_rabbit.js
index 8647ade2..66b5c6cf 100644
--- a/lib/static/hearty_rabbit.js
+++ b/lib/static/hearty_rabbit.js
@@ -94,8 +94,13 @@ function upload_file(file)
 		else
 		{
 			console.warn("Upload failure:", req.status);
+			alert("onload(): cannot upload file: " + req.statusText);
 		}
 	};
+	req.onerror = () =>
+	{
+		alert("onerror(): cannot upload file: " + req.statusText);
+	};
 	req.send(file);
 	show_lightbox("/loading.svg");
 }