I had the same problem. Have you solved the problem?

Same problem.

EDIT: After some more searching I found this thread:
https://social.technet.microsoft.com/Forums/ie/en-US/aec2c852-109a-4fc3-95f9-6fe61e779adf/rvest-readhtml-function-does-not-work?forum=ropen

The workaround, for now, seems to be uninstalling curl and httr, restarting R, reinstalling those packages, then setting the CURL_CA_BUNDLE system environment.

1. Open a new MRO session and remove the packages 'curl' and 'httr':

   remove.packages(c("curl","httr"))

2. Restart MRO and install the packages again, this time using 'install.packages()' function:

   install.packages(c("curl", "httr"))

3. Set the environment variable 'CURL_CA_BUNDLE':

   Sys.setenv(CURL_CA_BUNDLE="/utils/microsoft-r-open-3.4.3/lib64/R/lib/microsoft-r-cacert.pem")

############################################################################
Original comment:

Same problem here.

sessionInfo()
R version 3.4.3 (2017-11-30)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 16.04.4 LTS

Matrix products: default
BLAS: /opt/microsoft/ropen/3.4.3/lib64/R/lib/libRblas.so
LAPACK: /opt/microsoft/ropen/3.4.3/lib64/R/lib/libRlapack.so

locale:
[1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C LC_TIME=en_US.UTF-8 LC_COLLATE=en_US.UTF-8 LC_MONETARY=en_US.UTF-8 LC_MESSAGES=en_US.UTF-8 LC_PAPER=en_US.UTF-8 LC_NAME=C LC_ADDRESS=C
[10] LC_TELEPHONE=C LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C

attached base packages:
[1] stats graphics grDevices utils datasets methods base

other attached packages:
[1] curl_3.1 devtools_1.13.4 RevoUtils_10.0.7 RevoUtilsMath_10.0.1

loaded via a namespace (and not attached):
[1] httr_1.3.1 compiler_3.4.3 R6_2.2.2 tools_3.4.3 withr_2.1.1 yaml_2.1.16 memoise_1.1.0 git2r_0.20.0 digest_0.6.13

##################################################################################

Sys.getenv("CURL_CA_BUNDLE")
[1] ""
ie_get_proxy_for_url("https://www.google.com")
NULL
ie_proxy_info()
NULL
Sys.getenv("https_proxy")
[1] ""
readLines(base::url("https://httpbin.org/get"))
Error in readLines(base::url("https://httpbin.org/get")) :
cannot open the connection to 'https://httpbin.org/get'
In addition: Warning message:
In readLines(base::url("https://httpbin.org/get")) :
URL 'https://httpbin.org/get': status was 'Problem with the SSL CA cert (path? access rights?)'
Sys.getenv("CURL_CA_BUNDLE")
[1] ""

Hi, I tried to set CURL_CA_BUNDLE to /opt/microsoft/ropen/3.4.4/lib64/R/lib/microsoft-r-cacert.pem since the certificate exists in that path for my case. And before that, I also uninstalled RCurl (since there is no package named curl in the first place so I assume RCurl still the same thing) and httr. But still, I failed to install package from GitHub.

> devtools::install_github('IRkernel/IRkernel')
Installation failed: error setting certificate verify locations:
  CAfile: microsoft-r-cacert.pem
  CApath: none

Any suggestion?

EDIT: Apparently it didn't work because before that I tried to edit Rprofile.site using this #6 (comment) solution. After I undo that edit and then followed the solution provided by @jakekramer, now it works.

The problem is due to a change in the R package 'curl'.

You can workaround the issue as follows:

1). Open a new MRO session and remove the packages 'curl' and 'httr':

remove.packages(c("curl","httr"))

2). Restart MRO and install the packages again, this time using 'install.packages()' function:

install.packages(c("curl", "httr"))

3). Set the environment variable 'CURL_CA_BUNDLE':

Sys.setenv(CURL_CA_BUNDLE="/utils/microsoft-r-open-3.4.3/lib64/R/lib/microsoft-r-cacert.pem")

4). Try installing a package using install_github() from github(this should now work):

For example:

install_github("ropensci/tokenizer")

Go to your Renvironment location:
/opt/microsoft/rclient/3.4.3/runtime/R/etc/Renviron

insert following line with sudo access:
CURL_CA_BUNDLE=/opt/microsoft/rclient/3.4.3/runtime/R/lib/microsoft-r-cacert.pem

> file.edit('~/.Renviron')

then write:

CURL_CA_BUNDLE=/opt/microsoft/ropen/3.5.1/lib64/R/lib/microsoft-r-cacert.pem

This works for me.

don't have access to > file.edit('~/.Renviron')