The page you have selected has an HTTP 302 status code which is a redirection. The HTML rendering might be normal. Instead you should compare the response that you get during validation with the recorded one. If it was also an HTTP 302 with the same URL (except for the potential dynamic values) then you are fine. You can check the next request and again compare the server response with the recorded one. At some point the server did not send the same response that would explain why the script is failing afterwards.