What is wrong with mysqli query?

Question

PHP

Where is the error in this code? The database query is not executed.
I tried to enter a request through phpMyAdmin, everything works, but here it doesn’t.

$value = serialize($value);
        
        $mysqli = new mysqli(DB_HOST,DB_LOGIN,DB_PASS,DB_NAME); 
        $q = $mysqli->prepare("UPDATE `settings` SET `value` = ? WHERE `name` = 'groups'");
        $q->bind_param("s",$value);
        $q->execute();
        $q->close();
        $mysqli->close();

Answer 1

Please $q->execute();add after echo $mysqli->error;. Then the error text will be visible.