WebForm_PostBackOptions is undefine

Recentily I have migrated one of web project to Visual Studio 2008(ASP.Net 2.0) from Visual Studio 2003(ASP.Net 1.1) . After converting the application I was getting javascript error WebForm_PostBackOptions is undefine .

If custom HttpModule is written in your application then you have to check for the relativePath of the request in PreRequestHandlerExecute delegate. If the relativePath contains WebResource.axd then just return.

string relativePath=HttpUtils.GetRelativePath(application.Request.ApplicationPath, application.Request.Path);

if ("/webresource.axd".Equals(relativePath.ToLower()))
{
return;
}