根据OP中给出的代码，很难准确地告诉您哪里出了问题。请注意我所能做的，你永远不要使用create_function(), 这是一个可被黑客利用的安全线程。你应该避免完全使用它。而是利用适当的closures 这是在PHP 5.3中引入的。

为了帮助您，这里有一个基本框架，您可以使用它来构建小部件。请注意，由于使用了new short array syntax ([])

class Custom_Services extends WP_Widget 
{

    public function __construct() 
    {
        parent::__construct(
            \'widget_custom_service\', 
            _x( \'Custom Service Widget\', \'Custom Service Widget\' ), 
            [ \'description\' => __( \'Displays information from a custom service.\' ) ] 
        );
        $this->alt_option_name = \'widget_custom_service\';

        add_action( \'save_post\', [$this, \'flush_widget_cache\'] );
        add_action( \'deleted_post\', [$this, \'flush_widget_cache\'] );
        add_action( \'switch_theme\', [$this, \'flush_widget_cache\'] );
    }

    public function widget( $args, $instance ) 
    {
        $cache = [];
        if ( ! $this->is_preview() ) {
            $cache = wp_cache_get( \'widget_services\', \'widget\' );
        }

        if ( ! is_array( $cache ) ) {
            $cache = [];
        }

        if ( ! isset( $args[\'widget_id\'] ) ) {
            $args[\'widget_id\'] = $this->id;
        }

        if ( isset( $cache[ $args[\'widget_id\'] ] ) ) {
            echo $cache[ $args[\'widget_id\'] ];
            return;
        }

        ob_start();

        $title          = ( ! empty( $instance[\'title\'] ) ) ? $instance[\'title\'] : __( \'Category Posts\' );
        /** This filter is documented in wp-includes/default-widgets.php */
        $title          = apply_filters( \'widget_title\', $title, $instance, $this->id_base );

        // ADD YOUR CUSTOM PHP CODE HERE FOR EXECUTION TO DISPLAY ON FRONT END

        echo $args[\'after_widget\']; 

        if ( ! $this->is_preview() ) {
            $cache[ $args[\'widget_id\'] ] = ob_get_flush();
            wp_cache_set( \'widget_services\', $cache, \'widget\' );
        } else {
            ob_end_flush();
        }
    }

    public function update( $new_instance, $old_instance ) 
    {
        $instance                   = $old_instance;
        $instance[\'title\']          = strip_tags( $new_instance[\'title\'] );
        $this->flush_widget_cache();

        $alloptions = wp_cache_get( \'alloptions\', \'options\' );
        if ( isset($alloptions[\'widget_custom_service\']) )
            delete_option(\'widget_custom_service\');

        return $instance;
    }

    public function flush_widget_cache() 
    {
        wp_cache_delete(\'widget_services\', \'widget\');
    }

    public function form( $instance ) 
    {

        $title      = isset( $instance[\'title\'] ) ? esc_attr( $instance[\'title\'] ) : \'\';
        ?>

        <p>
            <label for="<?php echo $this->get_field_id( \'title\' ); ?>"><?php _e( \'Title:\' ); ?></label>
            <input class="widefat" id="<?php echo $this->get_field_id( \'title\' ); ?>" name="<?php echo $this->get_field_name( \'title\' ); ?>" type="text" value="<?php echo $title; ?>" />
        </p>

    <?php
    }

}

add_action( \'widgets_init\', function () 
{
    register_widget( \'Custom_Services\' );
});