I’ve searched the other similar answer but still no luck. I have content type Station with field Province and City. Form alter: function mymodule_form_alter(&$ form, FormStateInterface $ form_state, $ form_id) { if ($ form_id === ‘node_station_form’) { // kint($ form); $ form[‘field_province’][‘widget’][‘#ajax’] = [ ‘event’ => ‘change’, ‘callback’ => ‘mymodule_callback_example’, ‘wrapper’ => ‘edit-field-city-wrapper’, ‘method’ =>Read more