Install GNU Radio Companion

I am trying to install GNU Radio Companion 3.8 in Ubuntu 18.04. I followed the instructions written in the Wikipedia and watched some YouTube videos, but after writing the commands below, I got some errors as attached in the figure.

Commands:

sudo add-apt-repository ppa:gnuradio/gnuradio-releases

and

sudo add-apt-repository ppa:gnuradio/gnuradio-releases-3.8

I tried to click on these links on the terminal, but all them did not open. Any idea how to fix these errors?

You have wrong repositories in your system, see details below:

1. Qt4 from rock-core does not provide packages for 18.04 LTS, so should be removed by

   sudo add-apt-repository -r ppa:rock-core/qt4
   

2. Ubuntu 18.04 LTS (bionic) is actual release, so its packages are located in archive, not old-releases. You can fix this problem by using command below:

   sudo sed -i "s/mx.old-releases/archive/g" /etc/apt/sources.list /etc/apt/sources.list.d/*.list
   sudo sed -i "s/old-releases/archive/g" /etc/apt/sources.list /etc/apt/sources.list.d/*.list
   

3. For sure re-add correct repositories to the system

   sudo add-apt-repository "deb http://archive.ubuntu.com/ubuntu bionic main restricted universe multiverse"
   sudo add-apt-repository "deb http://archive.ubuntu.com/ubuntu bionic-updates main restricted universe multiverse"
   sudo add-apt-repository "deb http://archive.ubuntu.com/ubuntu bionic-security main restricted universe multiverse"
   sudo add-apt-repository "deb http://archive.ubuntu.com/ubuntu bionic-backports main restricted universe multiverse"
   

4. Ubuntu 18.04 LTS is supported release, so ESM is not needed for it, remove such repositories by

   sudo rm /etc/apt/preferences.d/ubuntu-esm-infra
   sudo rm /etc/apt/sources.list.d/ubuntu-esm-infra.list
   

Then update package lists as usual, install upgrades with new dependencies and install GRC from already correctly chosen GnuRadio's PPA:

sudo apt-get update
sudo apt-get dist-upgrade
sudo apt-get install gnuradio

To get 3.8 version you have to purge the master branch repository by

sudo apt-get install ppa-purge
sudo ppa-purge ppa:gnuradio/gnuradio-master

And also releases PPA by

sudo ppa-purge ppa:gnuradio/gnuradio-releases

To stay only with gnuradio-releases-3.8 PPA.