As being asked my one of my colleagues as she was facing this error soon after she launched the application in IE (the browser, Internet Explorer). It was a Struts based application and We digged around all the possibilities by looking at the flow to find out where the encoding has been specified.
I was sure that it has to deal with the encoding settings at the client side (obviously thats what the meaningful Exception says! lol..). The research continued with applicationResources.properties of struts, other application specific properties file, web.xml (to specify the encoding if any) etc., But no luck!!
The entire stack trace is below (fyi).
...... [here the application specific code goes -- PRIVACY and CONFIDENTIALITY :)]
Well, she found out the solution with the googling that the "Issue was with the browser (IE 7) " and it was a bug in it. She got the application up and running in IE 6 :) Cool.
Thought of posting it here so that it may be useful for others whoever faces this issue :).