Exception starting filter Seam Filter java.lang.ClassCastException: org.jboss.seam.servlet.SeamFilter cannot be cast to javax.servlet.Filter

Exception starting filter Seam Filter java.lang.ClassCastException: org.jboss.seam.servlet.SeamFilter cannot be cast to javax.servlet.Filter

Ever notice this error when deploying your application with Seam.

This usually happens due to two reasons.

• You have duplicate seam jars in your application (e.g. EAR/lib and WAR/WEB-INF/classes/lib)

• or

• You have a servlet-api jar bundled as part of your app, which you never should as your web server has it (tomcat/jboss/geronimo etc)

Hope this helps someone.. coz I’ve stumbled into this and solved it couple of times.