Safari causes an error when ajax call is made

Question

I have the following ajax call:

        some_function: function (s) {
            var list = [];
            $.ajax({
                type: 'POST',
                contentType: 'application/json; charset=utf-8',
                url: this.ws_base() + "/webService/someFunction",
                dataType: 'json',
                data: JSON.stringify({ s: s }),
                async: false,
                success: function (data) {
                    list = JSON.parse(data.some_functionResult);
                },
                error: function (xhr, err) {
                    this.display_alert("some_function error - readyState: " + xhr.readyState + "\nstatus: " + xhr.status);
                }
            });
            return list;
        }

On desktop chrome/firefox this will return a long string in json format. Which is what is expected.

In mobile Safari this will return go to the error condition with readyState 0 status 0

I think there has to be some sort of syntax hiccup that Chrome/FF is fine with but in IOS causes the error function to run?

Testing on IOS is hard at my org, so any insight on this would be much appreciated.