What should be the correct content of sources.list?

It’s getting worse and worse:

I’ve found the content of sources.list for debian bullseye.
I’ve backed up my sourses.list, I’ve put the content of sources.list as I found online in a new sources.list file and tried to run aptitude update.
I got the following error:

Get:1 http://deb.debian.org/debian bullseye InRelease [116 kB]
Err:1 http://deb.debian.org/debian bullseye InRelease
  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 648ACFD622F3D138 NO_PUBKEY 0E98404D386FA1D9 NO_PUBKEY 605C66F00D6C9793
Get:2 http://deb.debian.org/debian-security bullseye-security InRelease [44.1 kB]
Err:2 http://deb.debian.org/debian-security bullseye-security InRelease
  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 112695A0E562B32A NO_PUBKEY 54404762BBB6E853
Get:3 http://deb.debian.org/debian bullseye-updates InRelease [39.4 kB]
Err:3 http://deb.debian.org/debian bullseye-updates InRelease
  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 648ACFD622F3D138 NO_PUBKEY 0E98404D386FA1D9
Reading package lists... Done
W: GPG error: http://deb.debian.org/debian bullseye InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 648ACFD622F3D138 NO_PUBKEY 0E98404D386FA1D9 NO_PUBKEY 605C66F00D6C9793
E: The repository 'http://deb.debian.org/debian bullseye 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.
W: GPG error: http://deb.debian.org/debian-security bullseye-security InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 112695A0E562B32A NO_PUBKEY 54404762BBB6E853
E: The repository 'http://deb.debian.org/debian-security bullseye-security 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.
W: GPG error: http://deb.debian.org/debian bullseye-updates InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 648ACFD622F3D138 NO_PUBKEY 0E98404D386FA1D9
E: The repository 'http://deb.debian.org/debian bullseye-updates 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.

after that I tried to add the keys with

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 648ACFD622F3D138

and some other keys as well, but then I receive the following error:

Executing: /tmp/apt-key-gpghome.KOQBuUbjXw/gpg.1.sh --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 648ACFD622F3D138
gpg: failed to start the dirmngr '/usr/bin/dirmngr': No such file or directory
gpg: connecting dirmngr at '/tmp/apt-key-gpghome.KOQBuUbjXw/S.dirmngr' failed: No such file or directory
gpg: keyserver receive failed: No dirmngr

I’m pretty much lost right now…
:slight_smile: