Update the controller metric2d.

controllers/plugin_event.py

@@ -58,11 +58,16 @@ def metric2d():
             store = report.get_store_configuration()
             grid = report.get_grid_configuration()
 
-            img = graph.to_svg()
-            img = urllib.quote(img)
+            if graph.ax is not None:
+                img = graph.to_svg()
+                img = urllib.quote(img)
 
-            response.view = "plugin_event/grid_and_graph.html"
-            return dict(cfg_store=store, grid=grid, img=img, title=title)
+                response.view = "plugin_event/grid_and_graph.html"
+                return dict(cfg_store=store, grid=grid, img=img, title=title)
+
+            else:
+                response.view = "plugin_event/grid.html"
+                return dict(cfg_store=store, grid=grid, title=title)
 
         elif extension == "pdf":
             data = graph.to_pdf()