Global.asax in Asp.net website Publishing

It will build n it'll run successfully, when i try to publish it is showing the error, its showing any line no or any source.

Yes done, Its not showing any error while debugging, Only while publishing it is showing error.
Below is my code and am using it for error log.
void Application_Start(object sender, EventArgs e)
{
// Code that runs on application startup
if (!System.Diagnostics.EventLog.SourceExists("ERSite"))
{
System.Diagnostics.EventLog.CreateEventSource("ERSite", "ErrorLog");
}
}


void Application_Error(object sender, EventArgs e)
{
// Code that runs when an unhandled error occurs
Exception ex = Server.GetLastError();
if (ex != null)
{
ErrorLog el = new ErrorLog();
el.Log(ex);

Server.ClearError();

Response.Redirect("Error.aspx");
}
}