I'm having trouble installing a dependency on
libc6. I'm trying to follow the solution in this question but I get the following response from
sudo apt update:
Hit:1 http://archive.raspberrypi.org/debian stretch InRelease Hit:2 http://raspbian.raspberrypi.org/raspbian stretch InRelease Ign:3 http://apt.mopidy.com stretch InRelease Hit:4 http://apt.mopidy.com stretch Release Get:5 http://ftp.us.debian.org/debian sid InRelease [242 kB] Err:5 http://ftp.us.debian.org/debian sid InRelease The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 7638D0442B90D010 NO_PUBKEY 04EE7237B7D453EC Reading package lists... Done W: GPG error: http://ftp.us.debian.org/debian sid InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 7638D0442B90D010 NO_PUBKEY 04EE7237B7D453EC E: The repository 'http://ftp.us.debian.org/debian sid 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.
I've tried running
gpg --keyserver keyring.debian.org --recv-keys 7638D0442B90D010 and similar with different keyservers, but none of them respond. I really don't have any idea what I'm doing: what's the problem and how do I fix it?