Description:
------------
Mysql server is running php5.3. New webserver is running php7.1 (migrated from php5.3). When I try to connect Mysql server with ssl its not working.

    try {
    $dbh = new PDO($dsn, $user, $password, array(PDO::MYSQL_ATTR_SSL_KEY  => '/etc/mysql/client-key.pem',
                                                 PDO::MYSQL_ATTR_SSL_CERT => '/etc/mysql/client-cert.pem',
                                                 PDO::MYSQL_ATTR_SSL_CA   => '/etc/mysql/ca-cert.pem')
                  );
        echo "Connestion established";
    } catch (PDOException $e) {
        echo 'Connection failed: ' . $e->getMessage();
    }

>Connection failed: SQLSTATE[HY000] [2002]

>PDO::__construct(): SSL operation failed with code 1. OpenSSL Error messages:
error:1416F086:SSL routines:tls_process_server_certificate:certificate verify failed

But, When I remove SSL block from connection, its working fine. I don't know what's going on. May be version mismatch of server and client. Becasue I am using old public key and private key.

Is it because of mysql client and server version mismatch?

PS: I have upgraded php7 in webserver only.

Actual result:
--------------
PDO::__construct(): SSL operation failed with code 1. OpenSSL Error messages:
error:1416F086:SSL routines:tls_process_server_certificate:certificate verify failed