Dear Oleg: I've read the primer a few times trying to find the answer. However, I have not found any clue on how to deal with the problem. >From the page source, it was clear that the validation was triggered by the form's submission. Although the URL didn't change before and after the form submission, the hidden input __EVENTVALIDATION element's value changed. From the trace, I believe that was what caused server internal error of my code. Is there anyway in httpclient to catch the change of the page?
Many thanks, DRB
