Android – Overflow Menu and Back Button not showing in Collapsing Toolbar

I had the same issue, none from existing answers have helped me, surprising fix of my problem was in question description.

Solution for AppCompat Activity

So working collapsing toolbar with back button needs those few lines in controller onCreate method:

//change id to Your id
toolbar = (Toolbar) findViewById(R.id.toolbar); 
setSupportActionBar(toolbar);

//this line shows back button
getSupportActionBar().setDisplayHomeAsUpEnabled(true); 

Manifest of this activity ( notice parentActivityName attribute ):

<activity
  android:name=".SomeActivity"
  android:parentActivityName=".MainActivity"
  android:theme="@style/AppTheme.NoActionBar"/>

Template part:

<android.support.design.widget.AppBarLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:fitsSystemWindows="true"
    android:theme="@style/AppTheme.AppBarOverlay">

    <android.support.design.widget.CollapsingToolbarLayout
        android:id="@+id/collapsing_toolbar"
        android:layout_width="match_parent"
        android:layout_height="200dp"
        app:layout_scrollFlags="scroll|exitUntilCollapsed"
        app:contentScrim="@color/colorPrimary"
        android:fitsSystemWindows="true"
        app:expandedTitleGravity="center_horizontal"
        >

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="@android:color/transparent"
            app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
            app:layout_collapseMode="pin"
            />

    </android.support.design.widget.CollapsingToolbarLayout>

</android.support.design.widget.AppBarLayout>

Alternative solution ( also AppCompat Activity )

Controller onCreate method:

toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);

toolbar.setNavigationIcon(android.support.v7.appcompat.R.drawable.abc_ic_ab_back_material);
toolbar.setNavigationOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            onBackPressed();
        }
});

This approach uses the same manifest and template presented in first solution.