Problem with googleapis

Same here, suddenly the path ‘https://ajax.googleapis.com/ajax/libs/jqueryui/1/themes/base/jquery-ui.css?ver=3.5.1 is wrong…

I’m using 2.2.1 on WP 3.5.1 — is this an issue also in more current versions of datepicker?

To correct this, you can enqueue the styles from your theme. Just copy/paste this code into your functions.php file of your current WordPress theme:

add_action( 'wp_enqueue_scripts', 'x_datepicker_style' );

function x_datepicker_style() {
	// register style
	wp_register_style( 'date-picker', 'https://code.jquery.com/ui/1.9.1/themes/base/jquery-ui.css' );
	// load style
	wp_enqueue_style('date-picker');
}