diff --git a/superset-frontend/src/explore/components/controls/SelectControl.jsx b/superset-frontend/src/explore/components/controls/SelectControl.jsx
index 9b8baee14..283139ac7 100644
--- a/superset-frontend/src/explore/components/controls/SelectControl.jsx
+++ b/superset-frontend/src/explore/components/controls/SelectControl.jsx
@@ -102,10 +102,9 @@ export default class SelectControl extends React.PureComponent {
   // Beware: This is acting like an on-click instead of an on-change
   // (firing every time user chooses vs firing only if a new option is chosen).
   onChange(opt) {
-    let optionValue = null;
+    let optionValue = this.props.multi ? [] : null;
     if (opt) {
       if (this.props.multi) {
-        optionValue = [];
         opt.forEach(o => {
           // select all options
           if (o.meta === true) {
diff --git a/superset/viz.py b/superset/viz.py
index e63f2c080..de5d597f7 100644
--- a/superset/viz.py
+++ b/superset/viz.py
@@ -2701,7 +2701,7 @@ class EventFlowViz(BaseViz):
         entity_key = form_data["entity"]
         meta_keys = [
             col
-            for col in form_data["all_columns"]
+            for col in form_data["all_columns"] or []
             if col != event_key and col != entity_key
         ]