Proxmox TLS, SSH, Certificate Errors
Occasionally while adding/removing a node or making other significant changes to your Proxmox cluster, you'll get some errors about unauthorized SSH keys or Certificates. You might be unable to migrate VMs/containers, unable to use virtual consoles, or unable to access the web interface at all.
One example error:
tls_process_server_certificate: certificate verify failed (596)
Generally, executing the following command will fix it right up:
pvecm updatecerts -F && systemctl restart pvedaemon pveproxy
Sometimes, the nuclear option is required. That means deleting all instances of the problem node from SSH known_hosts, verifying /etc/hosts info is correct on each node, and then executing the following:
pvecm updatecerts -F
service pve-cluster stop && service corosync stop && service pvestatd stop && service pveproxy stop && service pvedaemon stop
service pve-cluster start && service corosync start && service pvestatd start && service pveproxy start
I have had these errors occur after reinstalling Proxmox on a node and attempting to rejoin the cluster with the same hostname/ip. Performing the steps above usually gets me back in business pretty quickly.