I'm trying to install MikTex on Ubuntu 18.04 following the instructions in the website.
The first command,
sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys D6BC243565B2087BC3F897C9277A7293F59E4889
gives the error
gpg: keyserver receive failed: Invalid argument
What could be the problem?