How to replace Woocommerce placeholder image URL? Just copy the codes below.
add_filter(
'woocommerce_placeholder_img_src',
function( $classes ){
if( !is_product() ) return; // this code is intended to single product only. Remove this for general changes.
return get_bloginfo( 'url' ) . '/wp-content/uploads/2016/03/placeholder.jpg';
}
);