How To Fix “NO_PUBKEY” Error in sudo apt update with Proton VPN

In this article, we will delve into how to fix the “NO_PUBKEY” error that you may encounter while running sudo apt update with Proton VPN. This error typically arises due to issues with the GPG key of ProtonVPN, which is a crucial component for the authentication of packages.

Understanding the “NO_PUBKEY” Error

The “NO_PUBKEY” error is a common issue that users face when updating their package lists in Linux. This error signifies that the system lacks the necessary public key to authenticate and download packages from a specific repository, in this case, ProtonVPN.

Solution 1: Removing ProtonVPN Files

The first solution involves removing the ProtonVPN files from the sources.list.d directory. Here’s how to do it:

1. Open your terminal. You can do this by searching for “terminal” in your applications or by using the shortcut Ctrl + Alt + T.
2. Navigate to the /etc/apt/sources.list.d directory by running the following command:

cd /etc/apt/sources.list.d

3. Remove the ProtonVPN files from the folder using the following commands:

sudo rm protonvpn-stable.list
sudo rm protonvpn-stable.list.distUpgrade
sudo rm protonvpn-stable.list.save

4. Finally, run sudo apt update again to see if the issue is resolved.

Solution 2: Unchecking ProtonVPN in Software & Updates

The second solution involves unchecking ProtonVPN in the “Software & Updates” application.

1. Open the “Software & Updates” application. You can find this in your applications menu.
2. Go to the “Other Software” tab.
3. Uncheck any items related to ProtonVPN.
4. Click “Close” and when prompted, click “Reload” to update the sources.
5. Run sudo apt update again to see if the error is resolved.

Solution 3: Adding ProtonVPN’s GPG Key

The third solution involves manually adding ProtonVPN’s GPG key.

1. Visit the ProtonVPN website and search for their GPG key.
2. Once you find the key, open the terminal and run the following command, replacing <public-key> with the actual key:

curl -fsSL 'https://keyserver.ubuntu.com/pks/lookup?op=get&search=0x<public-key>' | sudo gpg --dearmor -o /etc/apt/trusted.gpg.d/protonvpn-stable.gpg

3. Run sudo apt update again to see if the issue is resolved.

Conclusion

The “NO_PUBKEY” error is a common issue that Linux users encounter while updating their package lists. The solutions provided above should ideally resolve the issue. However, if you’re still facing problems, you may need to reach out to ProtonVPN support for further assistance. Remember, it’s crucial to keep your system’s package list updated to ensure optimal performance and security.