I just downloaded the VM of the Trac appliance (version 14.1) and installed it on our vsphere. This worked fine. The server is running and I can access webmin.

However every HTTP or HTTPS call to the IP address returned an internal server error.

I could track this error down to /var/www/index.html

This file contained two additional lines after the closing html tag, which rendered it invalid and led to an error message "TemplateSyntaxError: junk after document element: line".

After I manually deleted those additional lines, trac started to work...