I am having the same issue, with JRebel Agent 6.2.4.
After pressing two or three times F5 to reload a page, i got this trace:
2015-09-16 14:28:52 JRebel: Reloading configuration
set 16, 2015 2:28:52 PM org.apache.catalina.core.ApplicationDispatcher invoke
GRAVE: Servlet.service() for servlet Faces Servlet threw exception
java.lang.NullPointerException
at com.sun.faces.context.ApplicationMap.get(ApplicationMap.java:97)
at com.sun.faces.context.flash.ELFlash.getFlash(ELFlash.java:301)
at com.sun.faces.context.flash.FlashFactoryImpl.getFlash(FlashFactoryImpl.java:56)
at com.sun.faces.context.ExternalContextImpl.getFlash(ExternalContextImpl.java:1111)
at javax.faces.context.ExternalContextWrapper.getFlash(ExternalContextWrapper.java:991)
at com.sun.faces.lifecycle.Phase.handleBeforePhase(Phase.java:214)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:99)
at com.sun.faces.lifecycle.RestoreViewPhase.doPhase(RestoreViewPhase.java:123)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:198)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:658)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:721)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:466)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:391)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:318)
at org.apache.jsp.index_jsp._jspService(index_jsp.java:90)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
Mojarra 2.2.12, Apache Tomcat/8.0.23, Windows 7 x64, java 1.8.0_40-b25
No issues using 2.2.11
Is the fix only in nightly-build?
(i was having some issues to use this forum)