See Reactstrap issue 799

reactstrap/reactstrap#799

client/package.json

@@ -27,6 +27,7 @@
     "babel-polyfill": "^6.26.0",
     "bootstrap": "^4.1.3",
     "connected-react-router": "^5.0.1",
+    "custom-event-polyfill": "^1.0.6",
     "date-fns": "2.0.0-alpha.21",
     "graphql": "^14.0.2",
     "graphql-tag.macro": "^2.0.0",

client/src/index.js

@@ -1,6 +1,8 @@
-// TODO: Confirm if the polyfill is still needed.  Originally added for google search console, but that was before
-// adding unfetch and including Chrome 41 in the browser list
+// Begin Polyfills for IE 11
 import 'babel-polyfill'
+import 'custom-event-polyfill'
+// End IE 11 Polyfills
+
 import React from 'react'
 import { render, hydrate } from 'react-dom'
 import { createBrowserHistory } from 'history'

yarn.lock

@@ -3696,6 +3696,11 @@ currently-unhandled@^0.4.1:
   dependencies:
     array-find-index "^1.0.1"
 
+custom-event-polyfill@^1.0.6:
+  version "1.0.6"
+  resolved "https://registry.yarnpkg.com/custom-event-polyfill/-/custom-event-polyfill-1.0.6.tgz#6b026e81cd9f7bc896bd6b016a427407bb068db1"
+  integrity sha512-3FxpFlzGcHrDykwWu+xWVXZ8PfykM/9/bI3zXb953sh+AjInZWcQmrnmvPoZgiqNjmbtTm10PWvYqvRW527x6g==
+
 cyclist@~0.2.2:
   version "0.2.2"
   resolved "https://registry.yarnpkg.com/cyclist/-/cyclist-0.2.2.tgz#1b33792e11e914a2fd6d6ed6447464444e5fa640"