How to fix E: Unmet dependencies. Try 'apt --fix-broken install' with no packages in APT

First, update your package cache and try the automatic fix suggested by apt:

sudo apt-get update
sudo apt --fix-broken install

This command tells apt to download and install any missing dependencies. If this succeeds, your issue is resolved.

If the above fails, check if any packages are held (prevented from being upgraded/removed):

apt-mark showhold

If packages are held, they may prevent dependency resolution. You can unhold them with:

sudo apt-mark unhold package-name
sudo apt --fix-broken install

Replace package-name with the actual package name shown in the hold list.

For more detailed information about what's causing the dependency conflict:

sudo apt-get -o Debug::pkgProblemResolver=yes dist-upgrade

The verbose output will show which packages are conflicting and why. This helps you understand what's happening so you can make informed decisions about which packages to remove or downgrade.

The aptitude package manager is often better at resolving complex dependency conflicts than apt-get:

sudo apt-get install aptitude
sudo aptitude install -f

Aptitude uses more sophisticated algorithms to find solutions and may succeed where apt-get fails. It may suggest removing or downgrading conflicting packages.

If previous steps fail, you may need to remove the packages causing the conflict. First, use apt to show which packages are broken:

sudo apt-get check

Once you identify the problematic package, try a dry run first:

sudo apt-get remove --dry-run package-name

If the dry run looks safe, remove it:

sudo apt-get remove package-name
sudo apt --fix-broken install

Then you can reinstall the package or find a compatible alternative version.

If a package is causing conflicts, you can explicitly install a compatible version:

sudo apt-get install package-name=version-number

First, see available versions:

apt-cache policy package-name

This shows all available versions in your repositories. Choose a compatible one and install it explicitly.