After Effects: After Effects fails to render on OS X based render nodes, why?

If no user is logged in on the Mac OS X platform, then rendering might fail with the following message:

INIT_Processeses(), could not establish the default connection to the WindowServer

There are two workarounds to avoid this situation:

  • Login the EnFuzion user permanently;
  • Set the ownership of the After Effects aerender command to root with the following commands:
    cd /Applications/Adobe After Effects 6.5
    sudo chmod +s aerender
    sudo chown root aerender