Software⏱️ 2 min read📅 2026-06-03

How to Fix: Force update from unsigned repository

Force update from unsigned repository in Ubuntu 16.04

Quick Answer: Use the `--skip-untrusted` option with `apt-get update` to force the update, or add the public key manually and then run `apt-get update` again.

📋 Table of Contents

  1. 🚀 How to Add the Public Key
  2. 🎯 Final Words

To resolve the 'Force update from unsigned repository' error in Ubuntu 16.04, you need to add the public key of the Debian Multimedia repository to your system.

🚀 How to Add the Public Key

Method 1: Using the Command Line

  1. Step 1: Run the following command to add the public key:
apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 5C808C2B65558117

Method 2: Using the Web Interface

  1. Step 1: Open the Ubuntu Software Updates settings by running the following command:
sudo software-properties-gtk

Step 2: Add the Public Key from the Web Interface

  1. Step 1: Go to the 'Add a new key' section and enter the following GPG key ID: 5C808C2B65558117

🎯 Final Words

After adding the public key, you should be able to update your system without any issues. Make sure to run apt-get update and apt-get install deb-multimedia-keyring -y to complete the process.

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