Warning: Missing argument 2 for wpdb::prepare()

I need a help after upgrade wordpress to 3.5 version with uCan Post plugin.

In settings menu the bug is: Warning: Missing argument 2 for wpdb::prepare(), called in /home/xxx/xxx/wp-content/plugins/ucan-post/ucan-post-class.php on line 564 and defined in /home/xxx/xxx/wp-includes/wp-db.php on line 990

In materials/posts menu the bug is: Warning: Missing argument 2 for wpdb::prepare(), called in /home/xxx/xxx/wp-content/plugins/ucan-post/ucan-post-class.php on line 420 and defined in /home/xxx/xxx/wp-includes/wp-db.php on line 990

ucan-post-class.php on line 564 is: return $wpdb->get_results($wpdb->prepare(“SELECT user_login, ID FROM {$wpdb->users} ORDER BY user_login ASC”));

ucan-post-class.php on line 420 is: return $wpdb->get_results($wpdb->prepare(“SELECT * FROM {$this->ucan_db_submissions} ORDER BY id DESC”));

wp-db.php on line 990 is: function prepare( $query, $args ) {

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