PHP Oracle PDO连接失败。 代码或配置错误？

I'm trying to make a Oracle connection, this way:

define('dsn','oci:dbname=xxx.xxx.xxx.xxx:1521/XE');
define('dbuser','aaaa');
define('dbpass','bbbb');
try {
    $conn = new PDO(dsn,dbuser,dbpass);
} catch (PDOException $e) {
    echo $e->getmessage();
}

But I get the message SQLSTATE[]: pdo_oci_handle_factory: <> (ext\pdo_oci\oci_driver.c:631)

Is that an server error, at php.ini or what?

make sure you only have the correct oracle extension enebled. when you have multiple oracle extensions enabled this error occurs