Missing PUBKEY authentication key

fatal error: W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: file:/var/lib/preinstalled-pool jammy Release: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY E2C7F054CE9BCEA0

The NO_PUBKEY error is not uncommon in deb-bhased software repos, and there are tons of how-tos on fixing this.

However, the preinstalled-pool repo is actually the installer media, usually used as a temporary source for a very small number of packages.

You can remove this (and the error) by deleting the file /etc/apt/sources.list.d/preinstalled-pool.list, or disabling it by opening the file in your text editior and adding a “#” to the line beginning with “deb.”