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sudo apt-get update error
W: An 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 trusty Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 16126D3A3E5C1192 W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/trusty/Release तो क्या कोई मुझे …