We started to use VMs instead of containers a few months ago on our Proxmox cluster. We had some issues in the beginning but now it works well.
Today I came across a very irritating problem as I was updating our certificates. After the update I couldn’t restart the working VMs and got the following error message:
Failed to start VNC server: Our own certificate /etc/pve/local/pve-ssl.pem failed validation against /etc/pve/pve-root-ca.pem: The certificate hasn't got a known issuer
The web interface was working well with the new certificate, so I started to search for answers.
Long story short, I found a few posts about the problem, but neither of them worked. And then I opened another one, and BOOM: It struck me hard.