Test to reproduce:
=======
    public static void main(String[] args) throws Exception {
        JFrame frame = new JFrame();
        frame.setJMenuBar(new JMenuBar());
        ByteArrayOutputStream baos = new ByteArrayOutputStream(10000);
        new ObjectOutputStream(baos).writeObject(frame);
    }
=======

Exception:

Exception in thread "main" java.io.NotSerializableException: com.apple.laf.AquaMenuBarBorder
at java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1185)
at java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
at java.base/java.io.ObjectOutputStream.defaultWriteObject(ObjectOutputStream.java:442)
at java.desktop/javax.swing.JComponent.writeObject(JComponent.java:5579)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1031)
at java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
at java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
at java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
at java.base/java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1379)
at java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1175)
at java.base/java.io.ObjectOutputStream.access$300(ObjectOutputStream.java:163)
at java.base/java.io.ObjectOutputStream$PutFieldImpl.writeFields(ObjectOutputStream.java:1713)
at java.base/java.io.ObjectOutputStream.writeFields(ObjectOutputStream.java:483)
at java.desktop/java.awt.Container.writeObject(Container.java:3694)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1031)
at java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
at java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
at java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
at java.base/java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1379)
at java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1175)
at java.base/java.io.ObjectOutputStream.access$300(ObjectOutputStream.java:163)
at java.base/java.io.ObjectOutputStream$PutFieldImpl.writeFields(ObjectOutputStream.java:1713)
at java.base/java.io.ObjectOutputStream.writeFields(ObjectOutputStream.java:483)
at java.desktop/java.awt.Container.writeObject(Container.java:3694)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1031)
at java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
at java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
at java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
at java.base/java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1379)
at java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1175)
at java.base/java.io.ObjectOutputStream.access$300(ObjectOutputStream.java:163)
at java.base/java.io.ObjectOutputStream$PutFieldImpl.writeFields(ObjectOutputStream.java:1713)
at java.base/java.io.ObjectOutputStream.writeFields(ObjectOutputStream.java:483)
at java.desktop/java.awt.Container.writeObject(Container.java:3694)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1031)
at java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
at java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
at java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
at java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)