Hello
in c# Datetime is totally dependent of culture information of machine or server datetime if you change your datetime format it automatically change thats why give error.
for solving this you can send date in mm/dd/yyyy format and it is unique format for sql server you can easy enter it on to the database.
when you display it please change it into dd/mm/yyyy or your requirement.
var param1 = new Date();
var param2 = (param1.getMonth() + 1) + '/' + param1.getDate() + '/' + (param1.getFullYear() + 5);
i hope your problem will solve if not please comment.