After upgrading to ubuntu 20.04 from 18.04 unable to install php

Question

I have done a release upgrade from ubuntu 18.04 to 20.04. Removed previously installed PHP. Then I run

sudo apt install php-cli

but I encounter the error below:

The following packages have unmet dependencies:
 php7.4-cli : Depends: php7.4-common (= 7.4.3-4ubuntu2.4) but 7.4.8-1+ubuntu18.04.1+deb.sury.org+3 is to be installed
              Depends: php7.4-json but it is not going to be installed
              Depends: php7.4-opcache but it is not going to be installed
              Depends: php7.4-readline but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

so I suspect 7.4.8-1+ubuntu18.04.1+deb.sury.org+3 package is still active? I have checked /etc/apt/sources.list and /etc/apt/sources.list.d/ directory and didn't found any source matching that package.

Where else should I look?

Edit

apt policy php7.4-common

php7.4-common:
  Installed: 7.4.8-1+ubuntu18.04.1+deb.sury.org+3
  Candidate: 7.4.8-1+ubuntu18.04.1+deb.sury.org+3
  Version table:
 *** 7.4.8-1+ubuntu18.04.1+deb.sury.org+3 100
        100 /var/lib/dpkg/status
     7.4.3-4ubuntu2.4 500
        500 http://bd.archive.ubuntu.com/ubuntu focal-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu focal-security/main amd64 Packages
     7.4.3-4ubuntu1 500
        500 http://bd.archive.ubuntu.com/ubuntu focal/main amd64 Packages

Answer 1

You uninstalled php, but not it's dependencies, so there are still leftovers from the ppa (I guess it was ppa:ondrej/php).

Try autoremove, it may already be enough:

sudo apt autoremove

If not, you can manually uninstall the packages in question:

sudo apt remove php7.4-common

If that is not enough, it might help adding the ppa again and remove with ppa-purge:

sudo add-apt-repository ppa:ondrej/php
sudo apt install ppa-purge
sudo ppa-purge ppa:ondrej/php