HELP with java.lang.NullPointerException on doFilter

[gaston e lopez]

HI, I need some helo with this. I cant resolve.

I have the next error: javax.servlet.ServletException: java.lang.NullPointerException inside a method doFilter.
I dont know what else to do... I cant find the error.

org.apache.struts.action.RequestProcessor.processException(RequestProcessor.java:508)
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:415)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:225)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1858)
org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:446)
javax.servlet.http.HttpServlet.service(HttpServlet.java:734)
javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
org.apache.catalina.core.ApplicationFilterChain.servletService(ApplicationFilterChain.java:427)
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:333)
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214)
negocio.DAO.Hibernation.doFilter(Hibernation.java:126)
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:246)
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214)
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:313)
org.apache.catalina.core.StandardContextValve.invokeInternal(StandardContextValve.java:287)
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:218)
org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:648)
org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:593)
com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:94)
com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:98)
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:222)
org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:648)
org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:593)
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:587)
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:1093)
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:166)
org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:648)
org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:593)
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:587)
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:1093)
org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:291)
com.sun.enterprise.web.connector.grizzly.DefaultProcessorTask.invokeAdapter(DefaultProcessorTask.java:666)
com.sun.enterprise.web.connector.grizzly.DefaultProcessorTask.doProcess(DefaultProcessorTask.java:597)
com.sun.enterprise.web.connector.grizzly.DefaultProcessorTask.process(DefaultProcessorTask.java:872)
com.sun.enterprise.web.connector.grizzly.DefaultReadTask.executeProcessorTask(DefaultReadTask.java:341)
com.sun.enterprise.web.connector.grizzly.DefaultReadTask.doTask(DefaultReadTask.java:263)
com.sun.enterprise.web.connector.grizzly.DefaultReadTask.doTask(DefaultReadTask.java:214)
com.sun.enterprise.web.portunif.PortUnificationPipeline$PUTask.doTask(PortUnificationPipeline.java:382)
com.sun.enterprise.web.connector.grizzly.TaskBase.run(TaskBase.java:264)
com.sun.enterprise.web.connector.grizzly.ssl.SSLWorkerThread.run(SSLWorkerThread.java:106)

[Paul Clapham]

It looks to me like the answer is going to involve Struts, so since there's an identical copy of this post in the Struts forum, I'm locking this one.