I was following this instruction for installing R 4.0 in Ubuntu 18.04

$ sudo apt remove r-base

$ sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys E298A3A825C0D65DFD57CBB651716619E084DAB9

$ sudo add-apt-repository 'deb https://cloud.r-project.org/bin/linux/ubuntu bionic-cran40/'

$ sudo apt update

$ sudo apt install r-base

However I get this error message:

Reading package lists... Done

Building dependency tree

Reading state information... Done

Package r-base is not available, but is referred to by another package.

This may mean that the package is missing, has been obsoleted, or

is only available from another source

However the following packages replace it:

  r-base-core r-doc-info r-doc-html r-base-html r-base-core:i386



E: Package 'r-base' has no installation candidate

I'm using this version of Ubuntu:

$ uname -a

Linux ip-172-31-28-209 5.4.0-1059-aws #62~18.04.1-Ubuntu SMP Fri Oct 22 21:51:38 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux



$ lsb_release -cs

bionic

How can I resolve the issue?

Update

$ sudo apt-cache policy r-base

r-base:

  Installed: (none)

  Candidate: (none)

  Version table:

     4.1.2-1.1804.0 -1

         -1 https://cloud.r-project.org/bin/linux/ubuntu bionic-cran40/ Packages

     4.1.1-1.1804.0 -1

         -1 https://cloud.r-project.org/bin/linux/ubuntu bionic-cran40/ Packages

     4.1.0-1.1804.0 -1

         -1 https://cloud.r-project.org/bin/linux/ubuntu bionic-cran40/ Packages

     4.0.5-1.1804.0 -1

         -1 https://cloud.r-project.org/bin/linux/ubuntu bionic-cran40/ Packages

     4.0.4-1.1804.0 -1

         -1 https://cloud.r-project.org/bin/linux/ubuntu bionic-cran40/ Packages

     4.0.3-1.1804.0 -1

         -1 https://cloud.r-project.org/bin/linux/ubuntu bionic-cran40/ Packages

     4.0.2-1.1804.0 -1

         -1 https://cloud.r-project.org/bin/linux/ubuntu bionic-cran40/ Packages

     4.0.1-1.1804.0 -1

         -1 https://cloud.r-project.org/bin/linux/ubuntu bionic-cran40/ Packages

     4.0.0-1.1804.0 -1

         -1 https://cloud.r-project.org/bin/linux/ubuntu bionic-cran40/ Packages

     3.4.4-1ubuntu1 -1

         -1 http://ap-northeast-1.ec2.archive.ubuntu.com/ubuntu bionic/universe amd64 Packages

Update 2

$ sudo apt install r-base=4.1.2-1.1804.0

Reading package lists... Done

Building dependency tree

Reading state information... Done

Some packages could not be installed. This may mean that you have

requested an impossible situation or if you are using the unstable

distribution that some required packages have not yet been created

or been moved out of Incoming.

The following information may help to resolve the situation:



The following packages have unmet dependencies:

 r-base : Depends: r-base-core (>= 4.1.2-1.1804.0) but it is not installable

          Depends: r-recommended (= 4.1.2-1.1804.0) but it is not installable

          Recommends: r-base-html but it is not installable

          Recommends: r-doc-html but it is not installable

E: Unable to correct problems, you have held broken packages.