The PHPMyAdmin that is distributed by Ubuntu repos is incompatible with PHP 7.2+. This causes syntax errors with count(), as well as some other calls. You can resolve this by installing the most recent release from the PHPMyAdmin PPA, which is the latest copy built and packaged from source.
Run the following commands to install the Ubuntu PPA:
add-apt-repository ppa:phpmyadmin/ppa
apt-get -y update
export DEBIAN_FRONTEND=noninteractiveNow you can install PHPMyAdmin:
apt-get -yq install phpmyadmin