Hi,

There are three reasons can cause error 500.

1. In WebService add attribute [System.Web.Script.Services.ScriptService()] to class. 2. If you use another asp controls in the same aspx page add in 3. If yet you get error - try ValidateRequest="false" in the tag

Please check the following link about this error: http://www.benhblog.com/2008/09/method-error-500-and-ajax.html

Please refer to this faq which tells you how to locate the cause. It's usually much easier to find it our in your practical environment.