So I did this way nothing on the Debian and using https://www.virtualmin.com/download/
But I get immediatly an error.
I checked in /etc/apt/sources.list.d/virtualmin.list
there is a source :
deb [signed-by=/usr/share/keyrings/debian-virtualmin-7.gpg] Index of /vm/7/gpl/apt virtualmin main
The log gives
Get:10 Index of /download/repository sarge Release.gpg [173 B]
Ign:10 Index of /download/repository sarge Release.gpg
Reading package lists…
W: GPG error: http://webmin.mirror.somersettechsolutions.co.uk/repository sarge Release: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY D97A3AE911>
E: The repository ‘http://webmin.mirror.somersettechsolutions.co.uk/repository sarge Release’ is not signed.
W: GPG error: Index of /download/repository sarge Release: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY D97A3AE911F63C51
E: The repository ‘Index of /download/repository sarge Release’ is not signed.
Downloading repository metadata: Failed with error: 100
[2023-03-04 19:05:06 CET] [ERROR] Something went wrong with the previous command. Exiting.
It looks like this issue happened to several persons.
I follow all the advices from Ilia
apt install --reinstall ca-certificates
I noted that /etc/apt/auth.conf.d/virtualmin.conf file is not present