WP_Widget in … has not been in use since version 4.3.0. Use instead:/ Notice: The called constructor method for WP_Widget is deprecated since version 4.3.0!

Notification :

"Notice: The called constructor method for WP_Widget is deprecated since version 4.3.0!"

or

"WP_Widget in ... is no longer in use since version 4.3.0. Please use instead:"

Example : old code

class my_widget extends WP_Widget {// constructor

 function my_widget() {

 parent::WP_Widget(

 false,

 __( 'My Widget', 'my-widget' ),

 array( 'description' => __( 'My sample widget', 'my-widget' ) ) );

 }

// ...
 }>

Change the function my_widget with the function __construct and parent::WP_Widget or $this->WP_Widget with parent::__construct then you will get this new structure

class my_widget extends WP_Widget {

// constructor
 function __construct() {
 parent::__construct(
 false,
 __( 'My Widget', 'my-widget' ),
 array( 'description' => __( 'My sample widget', 'my-widget' ) ) );
 }

// ...
 }

If it is adjusted correctly, this message will disappear.