WordPress at a glance
function is not described

_wp_menus_changed() WP 4.9.0

Handle menu config after theme change.

This is an internal function for using it by WP core itself. It's not recommended to use this function in your code.

No Hooks.

Return

null. Nothing.

Usage

_wp_menus_changed();

Changelog

Since 4.9.0 Introduced.

Code of _wp_menus_changed() WP 5.7.2

<?php
function _wp_menus_changed() {
	$old_nav_menu_locations    = get_option( 'theme_switch_menu_locations', array() );
	$new_nav_menu_locations    = get_nav_menu_locations();
	$mapped_nav_menu_locations = wp_map_nav_menu_locations( $new_nav_menu_locations, $old_nav_menu_locations );

	set_theme_mod( 'nav_menu_locations', $mapped_nav_menu_locations );
	delete_option( 'theme_switch_menu_locations' );
}