diff --git a/daqviewer/daqviewer.py b/daqviewer/daqviewer.py
index 47da141..5fd9dc7 100644
--- a/daqviewer/daqviewer.py
+++ b/daqviewer/daqviewer.py
@@ -233,7 +233,7 @@ def read_json_data(json_data):
             html.Div()
         ])
 
-    elif json.loads(json_data)['error']:
+    elif 'error' in json.loads(json_data):
         filename = json.loads(json_data)['error']
         elements = html.Div([
             dcc.Graph(figure={