How to fix the server method failed Maximum length exceeded error when using ASP.NET AJAX

If you are using ASP.NET AJAX to create RIA's (Rich Internet Applications) you might run into the maximum length exceeded error.

This error occurs when you are trying to send too much data using ASP.NET AJAX from the client to the server and vice versa.

On the function call stack level this error occurs at System.Web.Script.Serialization.JavaScriptSerializer.Deserialize or at System.Web.Script.Services.RestHandler.InvokeMethod depending if you are sending or receiving data.

The problem is that the default maximum size (102400 characters) does not suffice when you try to transfer a significant amount of data.

To increase the maximum allowed send/receive data you need to change the MaxJsonLength Property.

To change the MaxJsonLength Property you can edit your web.config file.

Look for the following commented section in the web.config file:

Convert it to something along the following lines (see note below):

<jsonSerialization maxJsonLength="200000"><

converters>

converters>

jsonSerialization>

Note that in the example above the max size was set to 200,000 characters.

You should calculate and test the size you will need for your data (there might be a few bytes of overhead so take that into account).