Debian Stable에 최신 R 통계 패키지를 설치할 수 없습니다.

이 페이지의 지침에 따라 Debian Stable(Buster)에 최신 R 패키지를 설치하려고 합니다.https://cloud.r-project.org/

/etc/apt/sources.list에 다음을 추가했습니다.

deb https://cran.csiro.au/bin/linux/debian buster-cran35/

그러나 실행하면 sudo apt-get update다음과 같은 오류가 발생합니다.

$ sudo apt-get update
Hit:1 http://deb.debian.org/debian buster InRelease                   
Hit:2 http://deb.debian.org/debian-security buster/updates InRelease  
Hit:3 http://deb.debian.org/debian buster-updates InRelease          
Hit:4 http://deb.debian.org/debian buster-backports InRelease        
Get:5 https://cran.csiro.au/bin/linux/debian buster-cran35/ InRelease [4,375 B]
Err:5 https://cran.csiro.au/bin/linux/debian buster-cran35/ InRelease
  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY FCAE2A0E115C3D8A
Reading package lists... Done
W: GPG error: https://cran.csiro.au/bin/linux/debian buster-cran35/ InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY FCAE2A0E115C3D8A
E: The repository 'https://cran.csiro.au/bin/linux/debian buster-cran35/ InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

다음을 시도해도 GPG 오류를 제거할 수 없습니다.

sudo apt-get install debian-keyring

sudo launchpad-getkeys

sudo aptitude install debian-archive-keyring

이 오류를 어떻게 해결할 수 있나요?