Plesk:
If You see the Tomcat icon, do not click on it. That takes you to Plesk's
default Java Application server support on a shared JVM.
You should click the NGASI Appserver Manager icon 
, which may be under
the custom button section in your domain view.
Make sure the FTP User for the domain is set as the
"Application Server Default System User" assigned by your Administrator.
Then click the "NGASI AppServer Manager" icon to access NGASI.
Also check with your Administrator that the user was assigned access to
NGASI AppServer Manager.
NOTE: Make sure the FTP User Password does not contain #
Also refer to:
The page cannot be displayed because an internal server error has occurred.
Setting Wildcard Mapping to the Application Server forwards all
requests to the Application Server. This prevents other requests,
including Web Statistics, from being processed by the Web Server.
The server response will include an error similar to:
404 - /plesk-stat/webstat/
To get around the Web Statistics issue, create a subdomain
called "ngstats", that use the FTP user account of the main domain.
Then login to NGASI and reset the Wildcard mapping.
Now instead of using
http://mydomain.com/plesk-stat/webstat/
to view the Web Statistics, browse with the following URL:
http://ngstats.mydomain.com/plesk-stat/webstat/