Class not found when unmarshalling: android.support.v7.widget.Toolbar$SavedState

I didn't like provided solutions as it imposed on my layouts and architecture.

Here's what I did to make it work. If you look at your stacktrace the ClassNotFoundException is coming from the line on GoogleMaps. So if we just fix that, the issue is gone.

GoogleMaps pukes/throw an error when the savedInstanceState has other items in it besides it's own. The solution is to just give GoogleMaps it's own dedicated bundle.

// class property
private static final String KEY_MAP_SAVED_STATE = "mapState";

// class methods
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    mapView = findMapView();  // make your own method here
    Bundle mapState = (savedInstanceState != null)
            ? savedInstanceState.getBundle(KEY_MAP_SAVED_STATE): null;
    mapView.onCreate(mapState);
}

@Override
public void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    Bundle mapState = new Bundle();
    mapView.onSaveInstanceState(mapState);
    outState.putBundle(KEY_MAP_SAVED_STATE, mapState);
}

One thing to note is I'm not using the SupportMapFragment. I'm using a MapView directly. You may have to extend the SupportMapFragment so you can catch the hook methods and provide a blank/clean bundle

Upon rotation, your SupportMapFragment gets destroyed and recreated. Before it's destroyed, it writes its current state to a Parcel, to be used in restoring its state when recreated. The Fragment's saved state will include the state of its child Views, and since you've nested a Toolbar within it, it attempts to save and restore that, as well. The Toolbar class does not have an inner class SavedState necessary for that, so this process fails when trying to restore the Toolbar instance from the Parcel.

The solution is to not nest the Toolbar - or any other View, for that matter - within the <fragment> element. Instead, pull the <include> out of the <fragment>, and put them both in another ViewGroup; for example, a vertical LinearLayout, or a RelativeLayout.

Changing activity_map.xml to this worked, thanks again Mike.

<?xml version="1.0" encoding="utf-8" ?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <include
        android:id="@+id/toolbar"
        layout="@layout/toolbar" />

    <fragment xmlns:map="http://schemas.android.com/apk/res-auto"
        android:id="@+id/map"
        android:name="com.google.android.gms.maps.SupportMapFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

    </fragment>
</RelativeLayout>