How to fix this warning:call_user_func_array() expects exactly 2 parameters, 1 given in D:\wamp\www\…….\wp-includes\class-wp-hook.php on line 286

Replace 'call_user_func_array' with name of the function to be called to output the page content.

add_action('admin_menu', 'personalised_menu');
function personalised_menu()
{
   add_menu_page( 'Page Title', 'Blog', 'edit_posts', 'menu_slug',
       'display_main_page', 'dashicons-welcome-write-blog' );
   add_submenu_page( 'menu_slug', 'Add New Page', 'Add New', 'edit_posts','add_new_page', 
        'display_secondary_page' );
}

function display_main_page() {
    echo 'Content of "Page Title"';
}

function display_secondary_page() {
    echo 'Content of subpage';
}