Outlook通知订阅续订PATCH

Question

I am trying to renew notification subscription using below code.

        $token = json_decode($account->token, true);
        $newToken = json_decode($sync->refreshToken($token['refresh_token']), true);

        $headers = array(
            "Content-Type: application/json",
            "Authorization: Bearer " . $newToken['access_token']
        );

        $url = "https://outlook.office.com/api/v2.0/me/subscriptions/" . $token['events_hookId'];
        $res = $emailSync->runCurl($url, null, $headers, "PATCH");
        print_r($res);
    }

but its returning below error.

{"error":{"code":"RequestBodyRead","message":"An unexpected 'EndOfInput' node was found when reading from the JSON reader. A 'StartObject' node was expected."}}