How to fix Package 'package-name' is not available, but is referred to by another package in APT

First, refresh APT's metadata from all enabled repositories to ensure it has the latest package information:

sudo apt-get update

This command fetches the latest package lists from your repositories. If the missing package has already been removed upstream, this will clear it from APT's records.

Some packages are provided by the universe or multiverse repositories, which may be disabled on minimal installations. Enable them:

sudo add-apt-repository universe
sudo apt-get update

If multiverse is also needed:

sudo add-apt-repository multiverse
sudo apt-get update

Use apt-cache to search for the specific package name or similar alternatives:

apt-cache search package-name

This helps identify if the package exists under a different name, has been renamed, or if a replacement package is available.

You can also check the package details:

apt-cache show package-name

If the missing package truly no longer exists and isn't needed, remove any packages that depend on it:

sudo apt-get remove package-name

If you don't know which package references it, try:

sudo apt-get autoremove

This removes packages that are no longer needed.

Check your /etc/apt/sources.list file and any files in /etc/apt/sources.list.d/ for outdated or broken repository entries:

sudo nano /etc/apt/sources.list

Comment out or remove lines pointing to unavailable repositories. Then run:

sudo apt-get update

You can also use:

sudo apt-get autoremove

to clean up any lingering package metadata.