Hi, I’m trying to update my install of Ubuntu-Mate 18.04. I get errors basically saying that the repository info can’t be downloaded. Here’s the error output of sudo apt update:
Err:9 http://cdn-fastly.deb.debian.org/debian stretch-backports InRelease
The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 8B48AD6246925553 NO_PUBKEY 7638D0442B90D010
Reading package lists… Done
W: GPG error: http://cdn-fastly.deb.debian.org/debian stretch-backports InRelease: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 8B48AD6246925553 NO_PUBKEY 7638D0442B90D010
E: The repository ‘http://http.debian.net/debian stretch-backports InRelease’ is not signed.
N: Updating from such a repository can’t be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
All the other repositories are working. This is the main issue. I can’t remember though whether I put this Debian repository in or if it’s a default one and what installed packages are associated with it.
So how can I find out what packages are associated with it? Is this a repository that Ubuntu-mate came with installed? If not I’d rather find out what’s installed from it and get rid of it. If it is an important repo, how can I get it working?