I have a Seam 2.3.1 ear project generating the exception specified on the title of this post when getting the home page with the browser.
Following some other posts around (java.lang.IllegalStateException: A request must be associated with the context in order to load the known conversations when using JSF with 8.0.0.Alpha4) and [WFLY-1946] Severe error on deploy of ear: "Unable to obtain CDI 1.1 utilities for Mojarra" - JBoss Issue Tracker I finally followed the suggestion on the last and added the JSF 2.1 jars to the ear root classpath (/lib folder) and this fixed the problem.