YARN-8413. Flow activity page is failing with 'Timeline server failed with an error'. Contributed by Sunil Govindan.

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-ui/src/main/webapp/app/initializers/loader.js

@@ -105,7 +105,7 @@ function updateConfigs(application) {
     $.ajax({
       type: 'GET',
       dataType: 'json',
-      async: true,
+      async: false,
       context: this,
       url: getTimeLineURL(rmhost, isHttpsSchemeEnabled),
       success: function(data) {