Update problem key signature

[Raphaël POITEVIN <raphael.poitevin@gmail.com>]

Hello,

On a remote server at OVH provider, I upgraded from Debian 8 to 9 and 9
to 10. I did'nt care if the problem appears after the last migration,
because it's not my server, I just helped temporarily.

But now:
# apt-get update
Err:1 http://debian.mirrors.ovh.net/debian buster-updates InRelease
  The following signatures couldn't be verified because the public key
  is not available: NO_PUBKEY 04EE7237B7D453EC NO_PUBKEY
  648ACFD622F3D138
  Err:2 http://debian.mirrors.ovh.net/debian buster-backports InRelease
    The following signatures couldn't be verified because the public key
    is not available: NO_PUBKEY 04EE7237B7D453EC NO_PUBKEY
    648ACFD622F3D138
    Err:3 http://debian.mirrors.ovh.net/debian buster InRelease
      The following signatures couldn't be verified because the public
      key is not available: NO_PUBKEY 04EE7237B7D453EC NO_PUBKEY
      648ACFD622F3D138 NO_PUBKEY DCC9EFBF77E11517
      Get:4 http://security.debian.org buster/updates InRelease [65.4
      kB]
      Err:4 http://security.debian.org buster/updates InRelease
        The following signatures couldn't be verified because the public
        key is not available: NO_PUBKEY AA8E81B4331F7F50 NO_PUBKEY
        112695A0E562B32A
        Reading package lists... Done
        W: GPG error: http://debian.mirrors.ovh.net/debian
        buster-updates InRelease: The following signatures couldn't be
        verified because the public key is not available: NO_PUBKEY
        04EE7237B7D453EC NO_PUBKEY 648ACFD622F3D138
        E: The repository 'http://debian.mirrors.ovh.net/debian
        buster-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.
        W: GPG error: http://debian.mirrors.ovh.net/debian
        buster-backports InRelease: The following signatures couldn't be
        verified because the public key is not available: NO_PUBKEY
        04EE7237B7D453EC NO_PUBKEY 648ACFD622F3D138
        E: The repository 'http://debian.mirrors.ovh.net/debian
        buster-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.
        W: GPG error: http://debian.mirrors.ovh.net/debian buster
        InRelease: The following signatures couldn't be verified because
        the public key is not available: NO_PUBKEY 04EE7237B7D453EC
        NO_PUBKEY 648ACFD622F3D138 NO_PUBKEY DCC9EFBF77E11517
        E: The repository 'http://debian.mirrors.ovh.net/debian buster
        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://security.debian.org buster/updates
        InRelease: The following signatures couldn't be verified because
        the public key is not available: NO_PUBKEY AA8E81B4331F7F50
        NO_PUBKEY 112695A0E562B32A
        E: The repository 'http://security.debian.org buster/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.

I tried to change mirror.

I tried to reinstall debian-archive-keyring but I get a HTTP 404.

I downloaded from snapshot.debian.org debian-archive-keyring
2019.1+deb10u1 and installed with dpkg -i. But the same situation.

I checked apt-key fingerprint, its seems OK.

Thanks for your help.

Sincerly,
-- 
Raphaël
www.leclavierquibave.fr