32

This question already has an answer here:

I have asked this question before, but it was closed as a "duplicate." I can assure you that my scenario is original, as it does not refer to third party PPA's. I am having GPG problems with system updates. It says there is no public key available, and I have also been warned that my update information is outdated. Here's the terminal text:

W: A error occurred during the signature verification.
The repository is not updated and the previous index files will be used. GPG error:http://extras.ubuntu.com quantal Release: 
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 16126D3A3E5C1192

W: GPG error: http:// archive.canonical.com quantal Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5 NO_PUBKEY 3B4FE6ACC0B21F32
W: GPG error: http:// us.archive.ubuntu.com quantal Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5 NO_PUBKEY 3B4FE6ACC0B21F32
W: GPG error: http:// us.archive.ubuntu.com quantal-updates Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5 NO_PUBKEY 3B4FE6ACC0B21F32
W: GPG error: http:// us.archive.ubuntu.com quantal-backports Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5 NO_PUBKEY 3B4FE6ACC0B21F32
W: GPG error: http:// us.archive.ubuntu.com quantal-security Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5 NO_PUBKEY 3B4FE6ACC0B21F32
W: Failed to fetch http:// extras.ubuntu.com/ubuntu/dists/quantal/Release

W: Some index files failed to download. They have been ignored, or old ones used instead.

I have put spaces in the urls because new users are not allowed more than two hyperlinks per question.

Please don't just close this as a duplicate. It does not refer to third party PPA's, it refers to the standard update packages issued by Canonical.

marked as duplicate by Seth, Kevin Bowen, Radu Rădeanu, Basharat Sialvi, Warren Hill Jul 5 '13 at 6:09

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

79

Run these commands in the terminal:

sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 40976EAF437D05B5
sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 3B4FE6ACC0B21F32

This downloads the missing GPG keys (as mentioned in the original error message) from the Ubuntu GPG keyserver.

  • 4
    You can also add multiple keys with a single command: apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 3B4FE6ACC0B21F32 40976EAF437D05B5 – panticz.de Sep 19 '15 at 8:14

Not the answer you're looking for? Browse other questions tagged or ask your own question.