The length of the string exceeds the value set on the maxJsonLength property

JavaScriptSerialzer has a public property named MaxJsonLength according to

http://msdn.microsoft.com/en-us/library/system.web.configuration.scriptingjsonserializationsection.maxjsonlength.aspx

Now, where you are deserializing your json, use this

JavaScriptSerializer serializer = new JavaScriptSerializer();serializer.MaxJsonLength = Int32.MaxValue; //Or any size you want to use, basically int maxValue is 2GB, you shouldn't need this big json string to deserialize, else you are doing it wrong.myObject obj = serializer.Deserialize<myObject>(yourJsonString);

And this should work perfectly, I recently figured this out through msdn and solved a problem that was bugging me for long.

I know this is a very old thread at the time of my reading, and that WebMethod is not really a thing in ASP.NET MVC so this is somewhat tangential. But, if anyone runs across it -

If you use ASP.NET MVC There is an alternative to invoking JavaScriptSerializer directly, which is to initialize the JsonResult and set the MaxJsonLength property on the result itself:

    private JsonResult GetReallyBigJsonResult(object data, JsonRequestBehavior requestBehavior)    {            return new JsonResult()            {                ContentEncoding = Encoding.Default,                ContentType = "application/json",                Data = data,                JsonRequestBehavior = requestBehavior,                MaxJsonLength = int.MaxValue            };    }

Not knowing the size of your string but perhaps it still exceeds the max limit that you have set?

Ideally ajax scenarios are meant only for small to medium server side calls not for getting tons of data, and if you are getting a lot of data using the asynchronous request then you are asking for trouble.

See here for an alternative