AJAX JSON throw an error - 500: Internal Server Error

Hello

ajax call webmethod to sometimes internal server error throw please solution

function saveanswerwithrec() {
debugger;
var UserAnswerText = $('#Hdn_AnswerText').val();
var AnswerTextBack = '<%=AnswerText%>';
var ResultID = <%= ResultID%>;
var TestID = <%= TestID%>;
var UserID = <%= UserID%>;
var AnswerID = <%= AnswerID%>;
var QuesID = <%= QuesID%>;
var TestSetID = <%= TestSetID%>;

if (AnswerTextBack == '')
AnswerTextBack = '0';

$.ajax({
type: "POST",
url: "/users/NewTest.aspx/StopSaveAnswer",
contentType: "application/json; charset=utf-8",
data: "{'RId':'" + ResultID + "','HiddenText':'" + UserAnswerText + "','AnswerText':'" + AnswerTextBack + "','TestID':'" + TestID + "','UserID':'" + UserID + "','AnswerID':'" + AnswerID + "','QuesID':'" + QuesID + "','TestSetID':'" + TestSetID + "'}",
datatype: "json",
async: true,
cache: false,
success: function (success) {
debugger;
alert("successsssss");
$('#Hdn_AnswerText').val('');
$('.recodingStatus').text('Your answer has been uploaded successfully.').show();
},
error: function (error) {
//$('.recodingStatus').text('Your answer has been uploaded successfully.').show();
}
});
}




[WebMethod]
[ScriptMethod(UseHttpGet = false)]
public static bool StopSaveAnswer(Int64 ResultID, string HiddenText, string AnswerText, Int64 TestID, Int64 UserID, Int64 AnswerID, Int64 QuesID, Int64 TestSetID)
{
Int16 ResultStatus = 0;
CommonLib.WriteFile("ResultID - " + ResultID);
try
{
DateTime LocalTime = CommonLib.LocalDateTimeByBranchID(CommonLib.SessionBranchID());
if (HiddenText.StartsWith("data:audio/mp3;base64,"))
{
Byte[] Byts = Convert.FromBase64String(HiddenText.Replace("data:audio/mp3;base64,", ""));
String FileName = "/uploaded_files/" + Guid.NewGuid().ToString() + ".mp3";

string FilePath = HttpContext.Current.Server.MapPath("~" + FileName);
File.WriteAllBytes(FilePath, Byts);
AnswerText = FileName;
}
else
AnswerText = HiddenText;

ResultID = CCLTestresult.SaveRecord(ResultID, TestID, UserID, 0, LocalTime, 0, "", 0, 0, 0);
Int64 RtnAnsID = CCLQuesanstable.SaveRecord(AnswerID, int.Parse(QuesID.ToString()), AnswerText, UserID, "1", 0, ResultID, 0, "", 0);

AnswerText = "";
if (ResultStatus == 1)
{
DBConnection.ExecuteQuery("update ccl_testresult set resultStatus=1 where resultID in(select resultID from ccl_testresult inner join ccl_testtable on resultTestID=TestID where resultUserID=" + UserID + " and TestSetID=" + TestSetID + ")");
}
}
catch (Exception e)
{
//String EmailBody = "Test=" + Ltr_Title.Text + "" + "QuesID=" + QuesID + "" + "UserID=" + UserID + "" + "IsAnswered=" + IsAnswered + "";
//EmailBody += e.Message + "" + e.StackTrace + "";
//EmailBody += "AnswerText:" + Hdn_AnswerText.Value;
//WebEmail.SendEmail("webzeb.stuti@gmail.com", "CCL Tutorials - New Practice Test Error", EmailBody);
return false;