Okay I justed checked the package lists for PHP common (in main) and intl (in universe) in default archive and security repo:
- Index of /ubuntu/dists/bionic/main/binary-amd64
- Index of /ubuntu/dists/bionic/universe/binary-amd64
- Index of /ubuntu/dists/bionic/main/binary-amd64
- Index of /ubuntu/dists/bionic/universe/binary-amd64
All of them contain the PHP 7.2.3 packages without exception, no 7.2.24 version at all!
The same time the package pools of all those repos contain the PHP 7.2.24 packages as well (beside the 7.2.3 ones) by filename for bionic 18.04, matching the php7.2-common version that is about to be pulled as above user posts:
- Index of /ubuntu/pool/main/p/php7.2
- http://archive.ubuntu.com/ubuntu/pool/universe/p/php7.2/
- http://security.ubuntu.com/ubuntu/pool/main/p/php7.2/
- http://security.ubuntu.com/ubuntu/pool/universe/p/php7.2/
I can only imagine that Ubuntu released the new version and then reverted the change due to issues, or such. And now local package lists or cache might contain inconsistent data.
Please try the following:
apt clean
rm -Rf /var/lib/apt/lists/* /var/cache/apt/*
apt update
apt install php-intl
and see if it now installs without the dependency error.
And last resort btw is to manipulate the installer a way that it has changed upstream already, sadly one day after Pi-hole v5 release: https://github.com/pi-hole/pi-hole/pull/3204
sed -i 's/php-intl/${phpVer}-intl/' /etc/.pihole/automated\ install/basic-install.sh
Since the php7.2-intl package is already installed on your system, with this change, no additional PHP package will be installed, hence no dependency error.