更新html会话R

Question

我正在尝试更新html会话并移至网站的第二页，但出现错误：导航至javascript：__ doPostBack（'ctl00 $ ContentPlaceHolder1 $ UCNested $ grdRTAList'，'Page $ 2'） curl :: curl_fetch_memory（url，handle = handle）中的错误：   端口号以“ _”结尾

library(rvest)
url <- "http://rtais.wto.org/UI/PublicMaintainRTAHome.aspx"
pgsession <- html_session(url) %>% follow_link(css = 
"#ContentPlaceHolder1_lnkRTAList") # List of all RTAs in force
pgsession <- pgsession %>% 
follow_link(xpath = "//table[@id='ContentPlaceHolder1_UCNested_grdRTAList']//a[.='2']")