skywalking-java/docs/en/FAQ/EnhanceRequireObjectCache-Cast-Exception.md

Problem

When you start your application with the skywalking agent, you may find this exception in your agent log which means that EnhanceRequireObjectCache cannot be casted to EnhanceRequireObjectCache. For example:

ERROR 2018-05-07 21:31:24 InstMethodsInter :  class[class org.springframework.web.method.HandlerMethod] after method[getBean] intercept failure
java.lang.ClassCastException: org.apache.skywalking.apm.plugin.spring.mvc.commons.EnhanceRequireObjectCache cannot be cast to org.apache.skywalking.apm.plugin.spring.mvc.commons.EnhanceRequireObjectCache
	at org.apache.skywalking.apm.plugin.spring.mvc.commons.interceptor.GetBeanInterceptor.afterMethod(GetBeanInterceptor.java:45)
	at org.apache.skywalking.apm.agent.core.plugin.interceptor.enhance.InstMethodsInter.intercept(InstMethodsInter.java:105)
	at org.springframework.web.method.HandlerMethod.getBean(HandlerMethod.java)
	at org.springframework.web.servlet.handler.AbstractHandlerMethodExceptionResolver.shouldApplyTo(AbstractHandlerMethodExceptionResolver.java:47)
	at org.springframework.web.servlet.handler.AbstractHandlerExceptionResolver.resolveException(AbstractHandlerExceptionResolver.java:131)
	at org.springframework.web.servlet.handler.HandlerExceptionResolverComposite.resolveException(HandlerExceptionResolverComposite.java:76)
	...

Reason

This exception may be caused by hot deployment tools (spring-boot-devtool) or otherwise, which changes the classloader in runtime.

Resolution

1. This error does not occur under the production environment, since developer tools are automatically disabled: See spring-boot-devtools.
2. If you would like to debug in your development environment as usual, you should temporarily remove such hot deployment package in your lib path.