diff --git a/src/Java.Interop/Java.Interop/JavaException.cs b/src/Java.Interop/Java.Interop/JavaException.cs
index 0bfa3fd58..b07735b5a 100644
--- a/src/Java.Interop/Java.Interop/JavaException.cs
+++ b/src/Java.Interop/Java.Interop/JavaException.cs
@@ -38,7 +38,7 @@ public unsafe JavaException ()
 			var peer = JniPeerMembers.InstanceMethods.StartCreateInstance ("()V", GetType (), null);
 			Construct (ref peer, JniObjectReferenceOptions.CopyAndDispose);
 			JniPeerMembers.InstanceMethods.FinishCreateInstance ("()V", this, null);
-			JavaStackTrace    = GetJavaStack (PeerReference);
+			SetJavaStackTrace ();
 		}
 
 		public unsafe JavaException (string message)
@@ -55,7 +55,7 @@ public unsafe JavaException (string message)
 			} finally {
 				JniObjectReference.Dispose (ref native_message, JniObjectReferenceOptions.CopyAndDispose);
 			}
-			JavaStackTrace    = GetJavaStack (PeerReference);
+			SetJavaStackTrace ();
 		}
 
 		public unsafe JavaException (string message, Exception innerException)
@@ -72,7 +72,14 @@ public unsafe JavaException (string message, Exception innerException)
 			} finally {
 				JniObjectReference.Dispose (ref native_message, JniObjectReferenceOptions.CopyAndDispose);
 			}
-			JavaStackTrace    = GetJavaStack (PeerReference);
+			SetJavaStackTrace ();
+		}
+
+		protected JavaException (ref JniObjectReference reference, JniObjectReferenceOptions transfer, JniObjectReference throwableOverride)
+			: base (GetMessage (throwableOverride), GetCause (throwableOverride))
+		{
+			Construct (ref reference, transfer);
+			SetJavaStackTrace (throwableOverride);
 		}
 
 		public JavaException (ref JniObjectReference reference, JniObjectReferenceOptions transfer)
@@ -80,7 +87,7 @@ public JavaException (ref JniObjectReference reference, JniObjectReferenceOption
 		{
 			Construct (ref reference, transfer);
 			if (PeerReference.IsValid)
-				JavaStackTrace    = GetJavaStack (PeerReference);
+				SetJavaStackTrace ();
 		}
 
 		protected void Construct (ref JniObjectReference reference, JniObjectReferenceOptions options)
@@ -183,6 +190,13 @@ public override unsafe int GetHashCode ()
 		{
 			if (transfer == JniObjectReferenceOptions.None)
 				return null;
+			return GetMessage (reference);
+		}
+
+		static string? GetMessage (JniObjectReference reference)
+		{
+			if (!reference.IsValid)
+				return null;
 
 			var m = _members.InstanceMethods.GetMethodInfo ("getMessage.()Ljava/lang/String;");
 			var s = JniEnvironment.InstanceMethods.CallObjectMethod (reference, m);
@@ -193,12 +207,30 @@ public override unsafe int GetHashCode ()
 		{
 			if (transfer == JniObjectReferenceOptions.None)
 				return null;
+			return GetCause (reference);
+		}
+
+		static Exception? GetCause (JniObjectReference reference)
+		{
+			if (!reference.IsValid)
+				return null;
 
 			var m = _members.InstanceMethods.GetMethodInfo ("getCause.()Ljava/lang/Throwable;");
 			var e = JniEnvironment.InstanceMethods.CallObjectMethod (reference, m);
 			return JniEnvironment.Runtime.GetExceptionForThrowable (ref e, JniObjectReferenceOptions.CopyAndDispose);
 		}
 
+		protected void SetJavaStackTrace (JniObjectReference peerReferenceOverride = default)
+		{
+			if (!peerReferenceOverride.IsValid) {
+				peerReferenceOverride   = PeerReference;
+			}
+			if (!peerReferenceOverride.IsValid) {
+				return;
+			}
+			JavaStackTrace  = GetJavaStack (peerReferenceOverride);
+		}
+
 		unsafe string? GetJavaStack (JniObjectReference handle)
 		{
 			using (var StringWriter_class   = new JniType ("java/io/StringWriter"))
diff --git a/src/Java.Interop/Java.Interop/JavaObject.cs b/src/Java.Interop/Java.Interop/JavaObject.cs
index 22e382fba..02a69e061 100644
--- a/src/Java.Interop/Java.Interop/JavaObject.cs
+++ b/src/Java.Interop/Java.Interop/JavaObject.cs
@@ -2,29 +2,35 @@
 
 using System;
 using System.Diagnostics.CodeAnalysis;
+using System.Runtime.Serialization;
 
 namespace Java.Interop
 {
 	[JniTypeSignature ("java/lang/Object", GenerateJavaPeer=false)]
+	[Serializable]
 	unsafe public class JavaObject : IJavaPeerable
 	{
 		internal const DynamicallyAccessedMemberTypes Constructors = DynamicallyAccessedMemberTypes.PublicConstructors | DynamicallyAccessedMemberTypes.NonPublicConstructors;
 
 		readonly static JniPeerMembers _members = new JniPeerMembers ("java/lang/Object", typeof (JavaObject));
 
-		public int                  JniIdentityHashCode { get; private set; }
-		public JniManagedPeerStates JniManagedPeerState { get; private set; }
+		[NonSerialized] int                     identityHashCode;
+		[NonSerialized] JniManagedPeerStates    managedPeerState;
+
+		public int                  JniIdentityHashCode => identityHashCode;
+
+		public JniManagedPeerStates JniManagedPeerState => managedPeerState;
 
 #if FEATURE_JNIOBJECTREFERENCE_SAFEHANDLES
-		JniObjectReference  reference;
+		[NonSerialized] JniObjectReference  reference;
 #endif  // FEATURE_JNIOBJECTREFERENCE_SAFEHANDLES
 #if FEATURE_JNIOBJECTREFERENCE_INTPTRS
-		IntPtr                  handle;
-		JniObjectReferenceType  handle_type;
+		[NonSerialized] IntPtr                  handle;
+		[NonSerialized] JniObjectReferenceType  handle_type;
 	#pragma warning disable 0169
 		// Used by JavaInteropGCBridge
-		IntPtr                  weak_handle;
-		int                     refs_added;
+		[NonSerialized] IntPtr                  weak_handle;
+		[NonSerialized] int                     refs_added;
 	#pragma warning restore 0169
 #endif  // FEATURE_JNIOBJECTREFERENCE_INTPTRS
 
@@ -151,12 +157,12 @@ void IJavaPeerable.Finalized ()
 
 		void IJavaPeerable.SetJniIdentityHashCode (int value)
 		{
-			JniIdentityHashCode = value;
+			identityHashCode    = value;
 		}
 
 		void IJavaPeerable.SetJniManagedPeerState (JniManagedPeerStates value)
 		{
-			JniManagedPeerState = value;
+			managedPeerState    = value;
 		}
 
 		void IJavaPeerable.SetPeerReference (JniObjectReference reference)
diff --git a/src/Java.Interop/Java.Interop/JniRuntime.JniValueManager.cs b/src/Java.Interop/Java.Interop/JniRuntime.JniValueManager.cs
index 207359e61..55af4f7b4 100644
--- a/src/Java.Interop/Java.Interop/JniRuntime.JniValueManager.cs
+++ b/src/Java.Interop/Java.Interop/JniRuntime.JniValueManager.cs
@@ -97,8 +97,13 @@ public void ConstructPeer (IJavaPeerable peer, ref JniObjectReference reference,
 
 				var newRef  = peer.PeerReference;
 				if (newRef.IsValid) {
-					// Activation! See ManagedPeer.RunConstructor
-					peer.SetJniManagedPeerState (peer.JniManagedPeerState | JniManagedPeerStates.Activatable);
+					JniObjectReference.Dispose (ref reference, options);
+
+					// Activation? See ManagedPeer.Construct, CreatePeer
+					// Instance was already added, don't add again
+					if (peer.JniManagedPeerState.HasFlag (JniManagedPeerStates.Activatable)) {
+						return;
+					}
 					JniObjectReference.Dispose (ref reference, options);
 					newRef   = newRef.NewGlobalRef ();
 				} else if (options == JniObjectReferenceOptions.None) {
diff --git a/src/Java.Interop/PublicAPI.Unshipped.txt b/src/Java.Interop/PublicAPI.Unshipped.txt
index e0f851bb0..d4be03231 100644
--- a/src/Java.Interop/PublicAPI.Unshipped.txt
+++ b/src/Java.Interop/PublicAPI.Unshipped.txt
@@ -3,5 +3,7 @@ static Java.Interop.JniEnvironment.BeginMarshalMethod(nint jnienv, out Java.Inte
 static Java.Interop.JniEnvironment.EndMarshalMethod(ref Java.Interop.JniTransition transition) -> void
 virtual Java.Interop.JniRuntime.OnEnterMarshalMethod() -> void
 virtual Java.Interop.JniRuntime.OnUserUnhandledException(ref Java.Interop.JniTransition transition, System.Exception! e) -> void
+Java.Interop.JavaException.JavaException(ref Java.Interop.JniObjectReference reference, Java.Interop.JniObjectReferenceOptions transfer, Java.Interop.JniObjectReference throwableOverride) -> void
+Java.Interop.JavaException.SetJavaStackTrace(Java.Interop.JniObjectReference peerReferenceOverride = default(Java.Interop.JniObjectReference)) -> void
 Java.Interop.JniTypeSignatureAttribute.InvokerType.get -> System.Type?
 Java.Interop.JniTypeSignatureAttribute.InvokerType.set -> void