Console looks like colored blocks

[RokModTwo]

Not sure what happened, but had to power-off the PVE server. After restarting, console/shell is just colored blocks.

Tried changing to different shell (VNC, xterm.js)

How to fix this?

 

[dcsapak]

you have to allow firefox the html5 canvas features:

https://support.mozilla.org/en-US/kb/firefox-protection-against-fingerprinting