Cert chain has expired cert.
admin-sec@ns01a:~$ wget http://www.webmin.com/jcameron-key.asc
--2018-10-19 16:34:52-- http://www.webmin.com/jcameron-key.asc
Resolving www.webmin.com (www.webmin.com)... 216.105.38.10
Connecting to www.webmin.com (www.webmin.com)|216.105.38.10|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1320 (1.3K) [text/plain]
Saving to: ‘jcameron-key.asc’
jcameron-key.asc 100%[==========================================================>] 1.29K --.-KB/s in 0s
2018-10-19 16:34:53 (119 MB/s) - ‘jcameron-key.asc’ saved [1320/1320]
admin-sec@ns01a:~$ sudo apt-key add jcameron-key.asc
OK
admin-sec@ns01a:~$ sudo apt-get update
Ign:1 https://download.webmin.com/download/repository sarge InRelease
Hit:2 http://archive.ubuntu.com/ubuntu bionic InRelease
Hit:3 http://security.ubuntu.com/ubuntu bionic-security InRelease
Err:4 https://download.webmin.com/download/repository sarge Release
Certificate verification failed: The certificate is NOT trusted. The certificate chain uses expired certificate. Could not handshake: Error in the certificate verification. [IP: 104.207.151.13 443]
Hit:5 http://archive.ubuntu.com/ubuntu bionic-updates InRelease
Hit:6 http://archive.ubuntu.com/ubuntu bionic-backports InRelease
Reading package lists... Done
E: The repository 'https://download.webmin.com/download/repository sarge Release' no longer has a Release file.
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.
admin-sec@ns01a:~$