这是什么原因，突然报错，之前并没有问题。。。

RedisCacheManagerorg.apache.shiro.config.ConfigurationException: Unable to instantiate class [gvitech.citymakerbook.shiro.cache.RedisCacheManager] for object named 'cacheManager_redis'. Please ensure you've specified the fully qualified class name correctly.
at org.apache.shiro.config.ReflectionBuilder.createNewInstance(ReflectionBuilder.java:151)
at org.apache.shiro.config.ReflectionBuilder.buildObjects(ReflectionBuilder.java:119)
at org.apache.shiro.config.IniSecurityManagerFactory.buildInstances(IniSecurityManagerFactory.java:161)
at org.apache.shiro.config.IniSecurityManagerFactory.createSecurityManager(IniSecurityManagerFactory.java:124)
at org.apache.shiro.config.IniSecurityManagerFactory.createSecurityManager(IniSecurityManagerFactory.java:102)
at org.apache.shiro.config.IniSecurityManagerFactory.createInstance(IniSecurityManagerFactory.java:88)
at org.apache.shiro.config.IniSecurityManagerFactory.createInstance(IniSecurityManagerFactory.java:46)
at org.apache.shiro.config.IniFactorySupport.createInstance(IniFactorySupport.java:123)
at org.apache.shiro.util.AbstractFactory.getInstance(AbstractFactory.java:47)
at org.apache.shiro.web.env.IniWebEnvironment.createWebSecurityManager(IniWebEnvironment.java:203)
at org.apache.shiro.web.env.IniWebEnvironment.configure(IniWebEnvironment.java:99)
at org.apache.shiro.web.env.IniWebEnvironment.init(IniWebEnvironment.java:92)
at org.apache.shiro.util.LifecycleUtils.init(LifecycleUtils.java:45)
at org.apache.shiro.util.LifecycleUtils.init(LifecycleUtils.java:40)
at org.apache.shiro.web.env.EnvironmentLoader.createEnvironment(EnvironmentLoader.java:221)
at org.apache.shiro.web.env.EnvironmentLoader.initEnvironment(EnvironmentLoader.java:133)
at org.apache.shiro.web.env.EnvironmentLoaderListener.contextInitialized(EnvironmentLoaderListener.java:58)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4853)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5314)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1408)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1398)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.apache.shiro.util.UnknownClassException: Unable to load class named [gvitech.citymakerbook.shiro.cache.RedisCacheManager] from the thread context, current, or system/application ClassLoaders. All heuristics have been exhausted. Class could not be found.
at org.apache.shiro.util.ClassUtils.forName(ClassUtils.java:148)
at org.apache.shiro.util.ClassUtils.newInstance(ClassUtils.java:164)
at org.apache.shiro.config.ReflectionBuilder.createNewInstance(ReflectionBuilder.java:144)