It's FOSS

A Linux and Open Source Web Portal

You are here: Home / Tutorial / How to Fix “The following signatures couldn’t be verified” Error in Ubuntu Linux

How to Fix “The following signatures couldn’t be verified” Error in Ubuntu Linux

Last updated By 26 Comments

Ubuntu and update errors are inseparable. Every now and then I encounter errors while updating the system after adding a new source. The other day I was trying to install Mate desktop environment when I got this GPG error while updating the system:

W: GPG error: http://repo.mate-desktop.org saucy InRelease: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 68980A0EA10B4DE8

W GPG Error The following signatures couldn't be verified because the public key is not available:

It is quite evident from the error message itself that the said public key was not found in the system. What happens here is that you had added some third-party repository. Every such software has a signature mechanism so that your system know that you are downloading that particular software from the repository you had added.

If the developer changes his/her public key and then provides an update, your system raises an alarm that the public key it know is not found anymore.

In this quick post I’ll show you how to fix this W: GPG error: The following signatures couldn’t be verified because the public key is not available: NO error.

Fix GPG error: The following signatures couldn’t be verified

What we need to do is to fetch this public key in the system. Get the key number from the message. In the above message, the key is 68980A0EA10B4DE8. Now use that key in the following command:

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 68980A0EA10B4DE8

This will add the key to the system. Just do an sudo apt-get update and you should not see this error any more. I hope this solved the problem for you.

As I said, Ubuntu and update errors are inseparable. Here are some of the most common Ubuntu update errors:

Let me know in the comments if this quick tip helped you fix this error or not.


3 Shares

  • It doesn’t work for me.
    I get this:
    Executing: /tmp/apt-key-gpghome.uB4ieFIXTF/gpg.1.sh –keyserver keyserver.ubuntu.com –recv-keys F57D4F59BD3DF454
    gpg: key ADAE6AD28A8F901A: public key “Sublime HQ Pty Ltd ” imported
    gpg: Total number processed: 1
    gpg: imported: 1
    gpg: invalid key resource URL ‘/etc/apt/trusted.gpg.d/home:manuelschneid3r.gpg’
    gpg: keyblock resource ‘(null)’: General error
    gpg: key 7721F63BD38B4796: 2 signatures not checked due to missing keys
    gpg: key 1488EB46E192A257: 1 signature not checked due to a missing key
    gpg: key 3B4FE6ACC0B21F32: 3 signatures not checked due to missing keys
    gpg: key D94AA3F0EFE21092: 3 signatures not checked due to missing keys
    gpg: key 871920D1991BC93C: 1 signature not checked due to a missing key
    gpg: Total number processed: 16
    gpg: skipped new keys: 16

    Reply

  • Dear Mr.Prakash,
    Can you help me with this problem. I cant able to update sudo apt-get update

    Err:11 http://us.archive.ubuntu.com/ubuntu precise-security InRelease
    The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5
    Get:12 http://us.archive.ubuntu.com/ubuntu precise-updates InRelease [55.7 kB]
    Err:12 http://us.archive.ubuntu.com/ubuntu precise-updates InRelease
    The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5
    Get:13 http://us.archive.ubuntu.com/ubuntu precise-backports InRelease [55.7 kB]
    Err:13 http://us.archive.ubuntu.com/ubuntu precise-backports InRelease
    The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5
    Get:14 http://us.archive.ubuntu.com/ubuntu precise Release.gpg [198 B]
    Ign:14 http://us.archive.ubuntu.com/ubuntu precise Release.gpg
    Reading package lists… Done
    W: GPG error: http://archive.canonical.com/ubuntu precise Release: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5
    E: The repository ‘http://archive.canonical.com/ubuntu precise Release’ is not signed.
    N: Updating from such a repository can’t be done securely, and is therefore disabled by default.
    N: See apt-secure(8) manpage for repository creation and user configuration details.
    W: GPG error: http://extras.ubuntu.com/ubuntu precise Release: Detached signature file ‘/var/lib/apt/lists/partial/extras.ubuntu.com_ubuntu_dists_precise_Release.gpg’ is in unsupported binary format
    E: The repository ‘http://extras.ubuntu.com/ubuntu precise Release’ is not signed.
    N: Updating from such a repository can’t be done securely, and is therefore disabled by default.
    N: See apt-secure(8) manpage for repository creation and user configuration details.
    W: GPG error: http://us.archive.ubuntu.com/ubuntu precise-security InRelease: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5
    E: The repository ‘http://us.archive.ubuntu.com/ubuntu precise-security InRelease’ is not signed.
    N: Updating from such a repository can’t be done securely, and is therefore disabled by default.
    N: See apt-secure(8) manpage for repository creation and user configuration details.
    W: GPG error: http://us.archive.ubuntu.com/ubuntu precise-updates InRelease: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5
    E: The repository ‘http://us.archive.ubuntu.com/ubuntu precise-updates InRelease’ is not signed.
    N: Updating from such a repository can’t be done securely, and is therefore disabled by default.
    N: See apt-secure(8) manpage for repository creation and user configuration details.
    W: GPG error: http://us.archive.ubuntu.com/ubuntu precise-backports InRelease: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5
    E: The repository ‘http://us.archive.ubuntu.com/ubuntu precise-backports InRelease’ is not signed.
    N: Updating from such a repository can’t be done securely, and is therefore disabled by default.
    N: See apt-secure(8) manpage for repository creation and user configuration details.
    W: GPG error: http://us.archive.ubuntu.com/ubuntu precise Release: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5
    E: The repository ‘http://us.archive.ubuntu.com/ubuntu precise Release’ is not signed.
    N: Updating from such a repository can’t be done securely, and is therefore disabled by default.
    N: See apt-secure(8) manpage for repository creation and user configuration details.

    Reply

    • Precise Pangolin means Ubuntu 12.04.

      Ubuntu 12.04 reached end of life in 2017. It is not supported and hence you won’t be able to update or install new packages.

      You must not use it anymore. I suggest manually installing a newer version of Ubuntu based on your system specification. Make a backup of your data of course.

      Reply

  • Nope – exactly the same GPG eror message afterwards. Running on a secure Ubuntu image on Azure, which might be the problem.

    Reply

  • Thanks Abhishek. As I am using kali linux, I tried the keyserver as,

    gpg –keyserver pgpkeys.mit.edu –recv-key

    As it did not work, I tried using ubuntu keyserver.

    It worked.

    Thanks for the valuable suggestion.

    Regards,
    Saikat

    Reply
    • >
    Copy link
    CopyCopied