We just started getting this error on an Ubuntu18.04 system on apt update: Err:19 https://research.cs.wisc.edu/htcondor/ubuntu/8.8/bionic bionic Release Certificate verification failed: The certificate is NOT trusted. The received OCSP status response is invalid. Could not handshake: Error in the certificate verification. [IP: 128.105.7.58 443] Our apt source file: cat /etc/apt/sources.list.d/htcondor.list deb http://research.cs.wisc.edu/htcondor/ubuntu/8.8/bionic bionic contrib deb-src http://research.cs.wisc.edu/htcondor/ubuntu/8.8/bionic bionic contrib |