diff --git a/android/modules/ui/src/java/ti/modules/titanium/ui/NavigationWindowProxy.java b/android/modules/ui/src/java/ti/modules/titanium/ui/NavigationWindowProxy.java
index d343b764bf1..90b1eb49674 100644
--- a/android/modules/ui/src/java/ti/modules/titanium/ui/NavigationWindowProxy.java
+++ b/android/modules/ui/src/java/ti/modules/titanium/ui/NavigationWindowProxy.java
@@ -1,11 +1,12 @@
 /**
  * Appcelerator Titanium Mobile
- * Copyright (c) 2018 by Axway, Inc. All Rights Reserved.
+ * Copyright (c) 2018-2021 by Axway, Inc. All Rights Reserved.
  * Licensed under the terms of the Apache Public License
  * Please see the LICENSE included with this distribution for details.
  */
 package ti.modules.titanium.ui;
 
+import org.appcelerator.kroll.KrollPromise;
 import org.appcelerator.kroll.annotations.Kroll;
 import org.appcelerator.titanium.TiC;
 import org.appcelerator.titanium.proxy.TiWindowProxy;
@@ -27,7 +28,7 @@ public NavigationWindowProxy()
 
 	@Override
 	@Kroll.method
-	public void open(@Kroll.argument(optional = true) Object arg)
+	public KrollPromise<Void> open(@Kroll.argument(optional = true) Object arg)
 	{
 		// FIXME: Shouldn't this complain/blow up if window isn't specified?
 		if (!opened && getProperties().containsKeyAndNotNull(TiC.PROPERTY_WINDOW)) {
@@ -37,9 +38,11 @@ public void open(@Kroll.argument(optional = true) Object arg)
 				openWindow(rootView, arg);
 				fireEvent(TiC.EVENT_OPEN, null);
 			}
-			return;
+			return KrollPromise.create((promise) -> {
+				promise.resolve(null);
+			});
 		}
-		super.open(arg);
+		return super.open(arg);
 	}
 
 	@Kroll.method
diff --git a/android/modules/ui/src/java/ti/modules/titanium/ui/WindowProxy.java b/android/modules/ui/src/java/ti/modules/titanium/ui/WindowProxy.java
index 0070b0c9fa8..95925638856 100644
--- a/android/modules/ui/src/java/ti/modules/titanium/ui/WindowProxy.java
+++ b/android/modules/ui/src/java/ti/modules/titanium/ui/WindowProxy.java
@@ -1,6 +1,6 @@
 /**
  * Appcelerator Titanium Mobile
- * Copyright (c) 2013 by Appcelerator, Inc. All Rights Reserved.
+ * Copyright (c) 2013-2021 by Appcelerator, Inc. All Rights Reserved.
  * Licensed under the terms of the Apache Public License
  * Please see the LICENSE included with this distribution for details.
  */
@@ -11,6 +11,7 @@
 import java.util.HashMap;
 
 import org.appcelerator.kroll.KrollDict;
+import org.appcelerator.kroll.KrollPromise;
 import org.appcelerator.kroll.annotations.Kroll;
 import org.appcelerator.kroll.common.Log;
 import org.appcelerator.titanium.TiActivity;
@@ -105,7 +106,7 @@ public TiUIView createView(Activity activity)
 	}
 
 	@Override
-	public void open(@Kroll.argument(optional = true) Object arg)
+	public KrollPromise<Void> open(@Kroll.argument(optional = true) Object arg)
 	{
 		HashMap<String, Object> option = null;
 		if (arg instanceof HashMap) {
@@ -127,7 +128,7 @@ public void open(@Kroll.argument(optional = true) Object arg)
 		properties.remove(TiC.PROPERTY_BOTTOM);
 		properties.remove(TiC.PROPERTY_LEFT);
 		properties.remove(TiC.PROPERTY_RIGHT);
-		super.open(arg);
+		return super.open(arg);
 	}
 
 	@Override
diff --git a/android/titanium/src/java/org/appcelerator/titanium/proxy/TiWindowProxy.java b/android/titanium/src/java/org/appcelerator/titanium/proxy/TiWindowProxy.java
index 525a795bc98..1d02fb77693 100644
--- a/android/titanium/src/java/org/appcelerator/titanium/proxy/TiWindowProxy.java
+++ b/android/titanium/src/java/org/appcelerator/titanium/proxy/TiWindowProxy.java
@@ -1,6 +1,6 @@
 /**
  * Appcelerator Titanium Mobile
- * Copyright (c) 2009-2013 by Appcelerator, Inc. All Rights Reserved.
+ * Copyright (c) 2009-2021 by Appcelerator, Inc. All Rights Reserved.
  * Licensed under the terms of the Apache Public License
  * Please see the LICENSE included with this distribution for details.
  */
@@ -12,6 +12,7 @@
 import java.util.List;
 
 import org.appcelerator.kroll.KrollDict;
+import org.appcelerator.kroll.KrollPromise;
 import org.appcelerator.kroll.KrollProxy;
 import org.appcelerator.kroll.annotations.Kroll;
 import org.appcelerator.kroll.common.Log;
@@ -72,6 +73,7 @@ public abstract class TiWindowProxy extends TiViewProxy
 	protected boolean windowActivityCreated = false;
 	protected List<Pair<View, String>> sharedElementPairs;
 	public TiWindowProxy navigationWindow;
+	private KrollPromise openPromise;
 
 	public interface PostOpenListener {
 		void onPostOpen(TiWindowProxy window);
@@ -98,34 +100,39 @@ public TiUIView createView(Activity activity)
 
 	@Kroll.method
 	@SuppressWarnings("unchecked")
-	public void open(@Kroll.argument(optional = true) Object arg)
+	public KrollPromise<Void> open(@Kroll.argument(optional = true) Object arg)
 	{
 		if (opened || opening) {
-			return;
+			return KrollPromise.create((promise) -> {
+				promise.reject(new Throwable("Window is already opened or opening."));
+			});
 		}
 
-		waitingForOpen = new WeakReference<TiWindowProxy>(this);
-		opening = true;
-		KrollDict options = null;
-		TiAnimation animation = null;
+		openPromise = KrollPromise.create((promise) -> {
+			waitingForOpen = new WeakReference<TiWindowProxy>(this);
+			opening = true;
+			KrollDict options = null;
+			TiAnimation animation = null;
 
-		if (arg != null) {
-			if (arg instanceof KrollDict) {
-				options = (KrollDict) arg;
+			if (arg != null) {
+				if (arg instanceof KrollDict) {
+					options = (KrollDict) arg;
 
-			} else if (arg instanceof HashMap<?, ?>) {
-				options = new KrollDict((HashMap<String, Object>) arg);
+				} else if (arg instanceof HashMap<?, ?>) {
+					options = new KrollDict((HashMap<String, Object>) arg);
 
-			} else if (arg instanceof TiAnimation) {
+				} else if (arg instanceof TiAnimation) {
+					options = new KrollDict();
+					options.put("_anim", animation);
+				}
+
+			} else {
 				options = new KrollDict();
-				options.put("_anim", animation);
 			}
 
-		} else {
-			options = new KrollDict();
-		}
-
-		handleOpen(options);
+			handleOpen(options);
+		});
+		return openPromise;
 	}
 
 	@Kroll.getProperty(name = "closed")
@@ -505,6 +512,11 @@ public void run()
 		if (nativeView != null) {
 			nativeView.postInvalidate();
 		}
+
+		if (openPromise != null) {
+			openPromise.resolve(null);
+			openPromise = null;
+		}
 	}
 
 	protected void fillIntent(Activity activity, Intent intent)
diff --git a/common/Resources/ti.internal/extensions/ti/ui/tabgroup.js b/common/Resources/ti.internal/extensions/ti/ui/tabgroup.js
index e6848155ca2..ba7423877f3 100644
--- a/common/Resources/ti.internal/extensions/ti/ui/tabgroup.js
+++ b/common/Resources/ti.internal/extensions/ti/ui/tabgroup.js
@@ -75,7 +75,7 @@ if (OS_ANDROID) {
 	TabGroup.prototype.open = function (options) {
 
 		if (this.currentState === this.state.opened) {
-			return;
+			return Promise.reject(new Error('Window is already opened or opening.'));
 		}
 
 		this.currentState = this.state.opening;
@@ -104,9 +104,10 @@ if (OS_ANDROID) {
 		if (this._activeTab !== -1) {
 			this.setActiveTab(this._activeTab);
 		}
-		_open.call(this, options);
+		const result = _open.call(this, options);
 
 		this.currentState = this.state.opened;
+		return result;
 	};
 
 	const _addTab = TabGroup.prototype.addTab;
diff --git a/common/Resources/ti.internal/extensions/ti/ui/window.js b/common/Resources/ti.internal/extensions/ti/ui/window.js
index 275ddb7796c..9d27c8d974d 100644
--- a/common/Resources/ti.internal/extensions/ti/ui/window.js
+++ b/common/Resources/ti.internal/extensions/ti/ui/window.js
@@ -63,7 +63,7 @@ if (OS_ANDROID) {
 			}
 		});
 
-		_open.call(this, options);
+		return _open.call(this, options);
 	};
 
 	const _add = Window.prototype.add;