server - A WebGroup/Virtual Host to handle /appname has not been defined -

i following error message when try open application web (using 'appname' application name, root name of application - error displays app's actual name):

com.ibm.ws.webcontainer.internal.webcontainer handlerequest srve0255e: webgroup/virtual host handle /appname has not been defined.

as far can tell, application installed correctly , running on our websphere server (was 8.5).

i'm @ loss pursue in order resolve issue - possible issue application having?

map web module /appname in administration console, or use whatever context-root specified web module.