diff --git a/ui/app/adapters/sync/association.js b/ui/app/adapters/sync/association.js
index 15474c596e..1468a5bbc5 100644
--- a/ui/app/adapters/sync/association.js
+++ b/ui/app/adapters/sync/association.js
@@ -82,9 +82,14 @@ export default class SyncAssociationAdapter extends ApplicationAdapter {
       const association = Object.values(resp.data.associated_secrets).find((association) => {
         return association.mount === data.mount && association.secret_name === data.secret_name;
       });
+
+      // generate an id if an association is found
+      // (an association may not be found if the secret is being unsynced)
+      const id = association ? serializer.generateId(association) : undefined;
+
       return {
         ...association,
-        id: serializer.generateId(association),
+        id,
         destinationName: resp.data.store_name,
         destinationType: resp.data.store_type,
       };
diff --git a/ui/tests/integration/components/sync/secrets/page/destinations/destination/secrets-test.js b/ui/tests/integration/components/sync/secrets/page/destinations/destination/secrets-test.js
index d0f4834fc5..392c6295bf 100644
--- a/ui/tests/integration/components/sync/secrets/page/destinations/destination/secrets-test.js
+++ b/ui/tests/integration/components/sync/secrets/page/destinations/destination/secrets-test.js
@@ -7,6 +7,7 @@ import { module, test } from 'qunit';
 import { setupRenderingTest } from 'ember-qunit';
 import { setupEngine } from 'ember-engines/test-support';
 import { setupMirage } from 'ember-cli-mirage/test-support';
+import syncHandler from 'vault/mirage/handlers/sync';
 import { setupModels } from 'vault/tests/helpers/sync/setup-models';
 import hbs from 'htmlbars-inline-precompile';
 import { click, render } from '@ember/test-helpers';
@@ -24,6 +25,7 @@ module(
     setupModels(hooks);
 
     hooks.beforeEach(async function () {
+      syncHandler(this.server);
       this.server.post('/sys/capabilities-self', allowAllCapabilitiesStub());
       sinon.stub(this.owner.lookup('service:router'), 'transitionTo');
 
@@ -84,5 +86,55 @@ module(
       await click(menu.unsync);
       await click(PAGE.confirmButton);
     });
+
+    module('flash messages', function (hooks) {
+      hooks.beforeEach(function () {
+        const flashMessages = this.owner.lookup('service:flash-messages');
+
+        this.flashSuccessSpy = sinon.spy(flashMessages, 'success');
+        this.flashDangerSpy = sinon.spy(flashMessages, 'danger');
+      });
+
+      test('unsync should render flash messages', async function (assert) {
+        await click(PAGE.menuTrigger);
+
+        const { menu } = PAGE.associations.list;
+        await click(menu.unsync);
+        await click(PAGE.confirmButton);
+
+        assert.true(
+          this.flashSuccessSpy.calledWith('Unsync operation initiated.'),
+          'Success message is displayed'
+        );
+        assert.true(this.flashDangerSpy.notCalled);
+      });
+
+      test('sync now should render flash messages', async function (assert) {
+        await click(PAGE.menuTrigger);
+
+        const { menu } = PAGE.associations.list;
+        await click(menu.sync);
+
+        assert.true(
+          this.flashSuccessSpy.calledWith('Sync operation initiated.'),
+          'Success message is displayed'
+        );
+        assert.true(this.flashDangerSpy.notCalled);
+      });
+
+      test('it should show an error message when sync fails', async function (assert) {
+        this.server.post('/sys/sync/destinations/:type/:name/associations/set', () => {
+          return new Response(500);
+        });
+
+        await click(PAGE.menuTrigger);
+
+        const { menu } = PAGE.associations.list;
+        await click(menu.sync);
+
+        assert.true(this.flashSuccessSpy.notCalled);
+        assert.true(this.flashDangerSpy.calledOnce);
+      });
+    });
   }
 );