Permission error creating new dm and uploading files (rhel + posgresql)

Troubleshooting
5
  1. I have not tested an older 3.0 version on the new server
  2. 4.1.0 using this guide https://docs.mattermost.com/administration/legacy-upgrade.html
  3. where can i check the system_user role?
  4. yes, it’s a local filesystem with mattermost ownership
  5. I overwrote the 4.1.0 config.json with the one from 3.3.0

Thanks for the response.