How to fix W: There is no public key available for the following key IDs in APT

APTBEGINNERMEDIUM

This warning appears when apt cannot verify repository signatures because GPG keys are missing. It typically occurs after adding a new PPA or repository. You can fix it by importing the missing GPG keys from key servers.

What this error means

The "no public key available" warning occurs when apt-get update cannot verify the authenticity of packages from a repository. Every Debian/Ubuntu repository signs its packages with a GPG (GNU Privacy Guard) key for security verification. When apt tries to update but can't find the public key, it means either: 1. You've recently added a new repository (PPA) that apt doesn't yet know about 2. The repository's key has changed or been rotated 3. The key server is temporarily unavailable 4. Your system's keyring is out of sync While this is technically just a warning (not an error that stops updates), it indicates security verification is failing, which is worth fixing.

How to fix "W: There is no public key available for the following key IDs"

1Identify the missing key ID from the warning message

When you run apt-get update, the warning will show:

bash

W: There is no public key available for the following key IDs:
467B942D3A79BD29

Copy the key ID (the hexadecimal string like '467B942D3A79BD29'). You'll use this in the next step.

Note: The key ID shown might be the last 16 characters of a longer fingerprint. That's fine—it's unique enough to find the key.

2Import the key from Ubuntu's key server (recommended for Ubuntu)

On Ubuntu systems, use the Ubuntu key server for fastest retrieval:

bash

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys YOUR_KEY_ID

Replace YOUR_KEY_ID with the actual key ID. For example:

bash

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 467B942D3A79BD29

Once imported, you should see:

bash

gpg: key 467B942D3A79BD29: public key "..." imported

3Verify the key was imported and update apt

After importing, run apt-get update again to verify the key is now recognized:

bash

sudo apt-get update

The warning for that key should no longer appear. If you added multiple repositories, you may see warnings for additional missing keys—repeat steps 1-2 for each one.

You can also list all trusted keys with:

bash

apt-key list

4If Ubuntu key server is unavailable, use an alternative

If the Ubuntu key server is slow or unreachable, try a different key server:

bash

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys YOUR_KEY_ID

Or use pgp.mit.edu:

bash

sudo apt-key adv --keyserver pgp.mit.edu --recv-keys YOUR_KEY_ID

Or use keys.openpgp.org:

bash

sudo apt-key adv --keyserver keys.openpgp.org --recv-keys YOUR_KEY_ID

Try different servers if one fails.

5For specific repositories (alternative method with GPG)

If apt-key doesn't work (it's deprecated on newer systems), download and import the key directly using GPG:

bash

gpg --keyserver keyserver.ubuntu.com --recv-keys YOUR_KEY_ID
gpg --armor --export YOUR_KEY_ID | sudo apt-key add -

For specific repositories like Google Chrome or Microsoft packages, check their documentation for the exact key URL, then import with curl or wget:

bash

# For Google Chrome
wget -qO- https://dl.google.com/linux/linux_signing_key.pub | sudo apt-key add -

# For Microsoft packages
curl -fsSL https://packages.microsoft.com/keys/microsoft.asc | sudo gpg --dearmor -o /usr/share/keyrings/microsoft-prod.gpg

How to fix W: There is no public key available for the following key IDs in APT

What this error means

Typical symptoms

Common causes

How to fix "W: There is no public key available for the following key IDs"

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