Global Error on response

 Hi,

I am using Moneris Gateway API on objective c.

I am getting response like: 

<?xml version="1.0" encoding="UTF-8"?>

<response>

  <receipt>

    <Message>Global Error</Message>

    <ResponseCode>900</ResponseCode>

  </receipt>

</response>

I am using Moneris kit for Apple Pay on distribution. But getting this error.

Can anybody tell/help why this error occurs randomly with no consistency? Or what can be the reason of this error.

Thanks & Regards.