R语言运行CAfile: ? CApath: none这是什么鬼

《基于R语言的自动数据收集：网络抓取和文本挖掘实用指南》第十章，。其中数据准备方面，如下

> library(RCurl)

> library(XML)

> library(bitops)

> library(stringr)

> all_links<- character()

> new_results<-"government/announcements?keywords=&announcement_filter_option=all&topics[]=all&departments[]=all&world_locations[]=all&from_date=01/07/2010"

> signatures<- system.file("CurlSSL",cainfo="cacert.pem",package ="RCurl")

> while(length(new_results)>0){                                          

+           new_results <-str_c("https://www.gov.uk/",new_results)

+           results <-getURL(new_results,cainfo=signature)

+           results_tree <- htmlParse(results)

+           all_links <- c(all_links,xpathSApply(results_tree,"//li[@id]//a",xmlGetAttr,"href"))

+           new_results <-xpathSApply(results_tree,"//nav[@id='show-more-documents']//li[@class='next']//a",xmlGetAttr,"href")

+  }

Error in function(type, msg, asError = TRUE)  :

  error setting certificate verify locations:

  CAfile: ? CApath: none

> signatures

[1] "D:/ProgramFiles (x86)/R/R-3.3.0/library/RCurl/CurlSSL/cacert.pem"

有哪位大神可以帮着解决一下这报错啊

请问这个问题楼主解决了吗