با سلام
من برای نصب نرم افزار ها و همچنین آپدیت سیستم عامل دچار مشکل شده ام و خطای زیر نمایش داده می شود:
W: GPG error:
http://ir.archive.ubuntu.com lucid Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5
W: A error occurred during the signature verification. The repository is not updated and the previous index files will be used.GPG error:
http://ir.archive.ubuntu.com lucid-updates Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5
W: A error occurred during the signature verification. The repository is not updated and the previous index files will be used.GPG error:
http://security.ubuntu.com lucid-security Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5
W: Failed to fetch
http://ir.archive.ubuntu.com/ubuntu/dists/lucid-updates/Release W: Failed to fetch
http://security.ubuntu.com/ubuntu/dists/lucid-security/Release W: Some index files failed to download, they have been ignored, or old ones used instead.
ممنونم کمکم کنید