One moment it worked the next it didn’t. Why proxmox would be fingerprinting the console is beyond me. It shouldn’t be.
What’s happening is that if you have canvas blocker then launching the console for a VM it can cause this error message. Disable canvas blocker and you will be able to connect again properly.
Now to find a way to keep canvas blocker enabled and get in. As I said it worked one minute then not the next. Did they update canvas blocker?
I disabled it and launched the VM again from within Proxmox. That worked. I then turned canvas blocker back on and tried again. Nope, wouldn’t launch.
I then decided to leave it enabled and I closed the browser and then relaunched and tried again. This worked. So, something with Canvas blocker but it can sometimes be solved by closing the browser and relaunching.