NullPointerException at org.jboss.web.tomcat.tc5.WebCtxLoader.start(WebCtxLoader.java:130)

Call to org.apache.catalina.Deployer.start() always causes NPE if the application had been previously stopped by calling org.apache.catalina.Deployer.stop(). Looking at the source code WebCtxLoader().stop() clears reference: this.webContainer = null; which is never re-initialized again. WebCtxLoader().start() assumes that webContainer is never null, hence the NPE.