Brower and desktop app access stopped working

Description

Users cannot access RC via browser any more. For some users Windows Desktop 3.8.6 has also stopped working, for some it works fine.
Only thing which is displayed is a black blank screen. Have tried server reboot with no change.
Since server upgrade and docker migration both failes, we’re very stuck. Anyone have any good suggestions?

Server Setup Information

  • Version of Rocket.Chat Server: 4.3.1
  • Operating System: Ubuntu
  • Deployment Method: tar
  • Number of Running Instances: 1
  • NodeJS Version: v12.18.4
  • MongoDB Version: 5.0.6
  • Proxy: nginx (Also tested without)
  • Firewalls involved: none