Assembly: System.Web (in system.web.dll)
The exception that raises the Error event can be accessed by a call to the GetLastError method. If your application generates custom error output, suppress the default error message that is generated by ASP.NET by a call to the ClearError method.
If your Web application contains XML Web services, you cannot use the Error event for global exception handling of those services. The HTTP handler for XML Web services consumes any exception that occurs in an XML Web service and converts it to a SOAP fault prior to the Error being called. To handle XML Web service exceptions, build a SOAP extension to process Web service exceptions in a custom global exception handler. For more information, see Handling and Throwing Exceptions in XML Web Services.