The missing class "com/ctc/wstx/io/CharsetNames" is present inside the "$JBOSS_HOME/modules/org/codehaus/woodstox/main/woodstox-core-as*.jar" file.
So try adding the dependency to this module inside your application in order to make this Jar/classes available:
<?xml version="1.0" encoding="UTF-8"?>
<module name="org.codehaus.woodstox" />
Thank you for your suggestion. I have several module-dependencies but my problem is that I do not need this class within my code and all previous tries to deploy my ear succeeded. For one time I got this error and after the server-restart it was gone. Maybe there is an indirect dependency I don't know!? I will add this module-dependency but I think that anything didn't work during undeploying my old-version-ear and it was not removed cleanly - but this is only a guess.
EAP 6.4 - the same problem:: NoClassDefFoundError: com/ctc/wstx/io/DefaultInputResolver
What works is to restart Jboss / whole cluster. So far we didn't manage to find out any other working solution.