backport of commit 9c8a742

changelog/21503.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+ui: Surface DOMException error when browser settings prevent localStorage.
+```

ui/app/lib/local-storage.js

@@ -1,6 +1,20 @@
 export default {
+  isLocalStorageSupported() {
+    try {
+      const key = `__storage__test`;
+      window.localStorage.setItem(key, null);
+      window.localStorage.removeItem(key);
+      return true;
+    } catch (e) {
+      // modify the e object so we can customize the error message.
+      // e.message is readOnly.
+      e.errors = [`This is likely due to your browser's cookie settings.`];
+      throw e;
+    }
+  },
+
   getItem(key) {
-    var item = window.localStorage.getItem(key);
+    const item = window.localStorage.getItem(key);
     return item && JSON.parse(item);
   },
 

ui/app/routes/vault/cluster.js

@@ -5,6 +5,7 @@ import Route from '@ember/routing/route';
 import { task, timeout } from 'ember-concurrency';
 import Ember from 'ember';
 import getStorage from '../../lib/token-storage';
+import localStorage from 'vault/lib/local-storage';
 import ClusterRoute from 'vault/mixins/cluster-route';
 import ModelBoundaryRoute from 'vault/mixins/model-boundary-route';
 
@@ -82,6 +83,9 @@ export default Route.extend(ModelBoundaryRoute, ClusterRoute, {
   },
 
   model(params) {
+    // if a user's browser settings block localStorage they will be unable to use Vault. The method will throw the error and the rest of the application will not load.
+    localStorage.isLocalStorageSupported();
+
     const id = this.getClusterId(params);
     return this.store.findRecord('cluster', id);
   },