diff --git a/js/ui/scheduler/appointmentPopup/popup.js b/js/ui/scheduler/appointmentPopup/popup.js
index 7da083e5423d..ed93456ae823 100644
--- a/js/ui/scheduler/appointmentPopup/popup.js
+++ b/js/ui/scheduler/appointmentPopup/popup.js
@@ -243,7 +243,9 @@ export class AppointmentPopup {
     }
 
     triggerResize() {
-        this.popup && triggerResizeEvent(this.popup.$element());
+        if(this.popup) {
+            triggerResizeEvent(this.popup.$element());
+        }
     }
 
     _getMaxWidth(isRecurrence) {
@@ -254,11 +256,15 @@ export class AppointmentPopup {
     }
 
     changeSize(isRecurrence) {
-        const fullScreen = this._isPopupFullScreenNeeded();
-        this.popup.option({
-            fullScreen,
-            maxWidth: fullScreen ? '100%' : this._getMaxWidth(isRecurrence),
-        });
+        if(this.popup) {
+            const fullScreen = this._isPopupFullScreenNeeded();
+            this.popup.option({
+                fullScreen,
+                maxWidth: fullScreen
+                    ? '100%'
+                    : this._getMaxWidth(isRecurrence),
+            });
+        }
     }
 
     updatePopupFullScreenMode() {
diff --git a/testing/testcafe/tests/scheduler/appointmentForm/showAppointmentPopup.ts b/testing/testcafe/tests/scheduler/appointmentForm/showAppointmentPopup.ts
index 3bd7e1cd3258..a6d0429f48b9 100644
--- a/testing/testcafe/tests/scheduler/appointmentForm/showAppointmentPopup.ts
+++ b/testing/testcafe/tests/scheduler/appointmentForm/showAppointmentPopup.ts
@@ -3,7 +3,7 @@ import Scheduler from '../../../model/scheduler';
 import createWidget from '../../../helpers/createWidget';
 import url from '../../../helpers/getPageUrl';
 
-fixture`Timeline Appointments`
+fixture`Appointment Form`
   .page(url(__dirname, '../../container.html'));
 
 const showAppointmentPopup = ClientFunction(() => {
@@ -28,3 +28,35 @@ test('Invoke showAppointmentPopup method shouldn\'t raise error if value of curr
   currentDate: new Date(2021, 2, 25).toISOString(),
   height: 600,
 }, true));
+
+test('Show appointment popup if deffereRendering is false (T1069753)', async (t) => {
+  const scheduler = new Scheduler('#container');
+  const appointment = scheduler.getAppointmentByIndex(0);
+
+  await t
+    .doubleClick(appointment.element)
+    .expect(scheduler.appointmentPopup.isVisible)
+    .ok();
+}).before(async () => {
+  await ClientFunction(() => {
+    (window as any).DevExpress.ui.dxPopup.defaultOptions({
+      options: {
+        deferRendering: false,
+      },
+    });
+  })();
+
+  await createWidget('dxScheduler', {
+    dataSource: [{
+      text: 'Test',
+      startDate: new Date(2021, 2, 29, 10),
+      endDate: new Date(2021, 2, 29, 11),
+    }],
+    views: ['day'],
+    currentView: 'day',
+    currentDate: new Date(2021, 2, 29),
+    startDayHour: 9,
+    endDayHour: 12,
+    width: 400,
+  }, true);
+});