Hibernate’s migration guide mentions that WebLogic uses a different version of ANTLR causing this exception.
A work around for this problem (differnet from what Hibernate mentions) is to set the “prefer-web-inf-classes” element in weblogic.xml to true.
<weblogic-web-app> .... <container-descriptor> <prefer-web-inf-classes>true</prefer-web-inf-classes> </container-descriptor> .... </weblogic-web-app>
I encountered this problem several months ago while running under WebLogic 8.x. Interestingly, it still exists in WebLogic 10.x server.