How to fix E: Packages were downgraded and -y was used without --allow-downgrades in APT

When using apt with -y to install a specific older version of a package, include the --allow-downgrades flag:

sudo apt install -y --allow-downgrades package-name=version

Example:

sudo apt install -y --allow-downgrades docker-ce=5.20.10~3-0~ubuntu-focal

If you are using Ansible, ensure your apt module includes the allow_downgrade parameter:

- name: Install specific package version
  ansible.builtin.apt:
    name: "{{ package_name }}={{ package_version }}"
    state: present
    allow_downgrade: yes

Note: Even with allow_downgrade set, you may need to ensure the generated apt command includes --allow-downgrades for Ansible versions that have this limitation.

If running automated upgrades via cron or CI/CD pipelines, modify your upgrade command:

Old (failing):

apt update && apt upgrade -y

New (if downgrades are needed):

apt update && apt upgrade -y --allow-downgrades

Better alternative - use unattended-upgrades:

sudo apt install unattended-upgrades
sudo dpkg-reconfigure unattended-upgrades

The unattended-upgrades package handles version conflicts intelligently without manual flag management.

Before applying the --allow-downgrades flag, understand why the downgrade is happening:

# Check currently installed version
apt list --installed | grep package-name

# Check available versions in repositories
apt policy package-name

# Check what apt would do with a dry run
apt install -y --allow-downgrades --simulate package-name=version

Only proceed with the actual installation if the simulation looks correct.