Rocket.chat 3.11 not finding / showin pdf after migration

Description

Hi there,
we migrated rocket.chat 3.11 from docker-container to standalone ubuntu 20.04 installation. Everything is working but the preview of pdf files. Instead of showing them we get an “404 page not found” message


Download of the pdf ist working though. this happens with firefox and chrome browser. In Desktop App (ubuntu 20.04) the download of the pdf opens up automatically

Server Setup Information

  • Version of Rocket.Chat Server: 3.11
  • Operating System: ubuntu20.04
  • Deployment Method: standalone install according to rocket.chat documentation
  • Number of Running Instances: 1
  • DB Replicaset Oplog: yes
  • NodeJS Version: 12.18.4
  • MongoDB Version: 4.0.22
  • Proxy: nginx
  • Firewalls involved: no

Any additional Information

things worked on the old docker installation but not after the migration

thanks a lot

cheers
mrhubber