# Pastebin cY023RXM Err:7 https://packagecloud.io/slacktechnologies/slack/debian jessie InRelease The following signatures couldn't be verified because the public key is not available: NO_PUBKEY C6ABDCF64DB9A0B2 Reading package lists... Done Building dependency tree... Done Reading state information... Done 1 package can be upgraded. Run 'apt list --upgradable' to see it. W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: https://packagecloud.io/slacktechnologies/slack/debian jessie InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY C6ABDCF64DB9A0B2 W: Failed to fetch https://packagecloud.io/slacktechnologies/slack/debian/dists/jessie/InRelease The following signatures couldn't be verified because the public key is not available: NO_PUBKEY C6ABDCF64DB9A0B2 W: Some index files failed to download. They have been ignored, or old ones used instead.