How to fix E: Sub-process /usr/bin/dpkg returned an error code (2) in APT

The most common fix is to reconfigure all packages that are installed but not properly configured:

sudo dpkg --configure -a

The -a flag tells dpkg to configure all unconfigured packages. This resolves issues where package installation was incomplete or interrupted.

If reconfiguring dpkg doesn't resolve the issue, use apt to fix broken dependencies:

sudo apt --fix-broken install

This command will attempt to resolve dependency issues and complete interrupted installations. The --fix-broken (or -f) flag specifically addresses broken package dependencies.

If the above steps don't work, dpkg may be blocked by lock files that weren't cleaned up properly. Remove them carefully:

sudo rm /var/lib/dpkg/lock
sudo rm /var/lib/apt/lists/lock
sudo rm /var/cache/apt/archives/lock

After removing these lock files, attempt to run your apt command again. You may also need to reconfigure dpkg again with sudo dpkg --configure -a.

The dpkg updates directory may be missing. Create it if it doesn't exist:

sudo mkdir -p /var/lib/dpkg/updates

Then update your package lists and try again:

sudo apt update
sudo apt upgrade

This directory is used by dpkg to track ongoing operations and is sometimes removed during system cleanup or after crashes.

If a specific package's metadata is corrupted (evident from error messages mentioning a specific package), you can remove its info file:

sudo rm /var/lib/dpkg/info/[package-name].list

Replace [package-name] with the actual package name from the error message. After removal, update and upgrade:

sudo apt update
sudo apt upgrade

Use this method only when you've identified the specific problematic package.

If none of the above fixes work, there may be underlying file system corruption. Check your system logs for filesystem errors:

sudo dmesg | grep -i error

Look for messages about filesystem issues. If you find concerning errors, you may need to run filesystem check tools like fsck (ideally in single-user mode or from a live USB), but be cautious as this can be destructive if run incorrectly.