org.apache.shiro.UnavailableSecurityManagerException: No SecurityManager accessible to the calling code, either bound to the org.apache.shiro.util.ThreadContext or as a vm static singleton. This is an invalid application configuration.
at org.apache.shiro.SecurityUtils.getSecurityManager(SecurityUtils.java:123)
at org.apache.shiro.subject.Subject$Builder.(Subject.java:627)
at org.apache.shiro.SecurityUtils.getSubject(SecurityUtils.java:56)
at com.beefend.forter.dbforter.utils.UserSessionListener.sessionDestroyed(UserSessionListener.java:28)
at org.apache.catalina.session.StandardSession.expire(StandardSession.java:824)
at org.apache.catalina.session.StandardSession.isValid(StandardSession.java:682)
at org.apache.catalina.session.ManagerBase.processExpires(ManagerBase.java:552)
at org.apache.catalina.session.ManagerBase.backgroundProcess(ManagerBase.java:537)
at org.apache.catalina.core.StandardContext.backgroundProcess(StandardContext.java:5543)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1372)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1376)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1376)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1344)
at java.lang.Thread.run(Unknown Source)
抛这个异常怎么解决