这个问题困扰我一个多小时了，等会解决完我就来回答。
2018-06-25 17:34:24,774 [qtp183264084-12] ERROR - Cannot forward to error page for request [/kaptcha] as the response has already been committed. As a result, the response may have the wrong status code. If your application is running on WebSphere Application Server you may be able to resolve this problem by setting com.ibm.ws.webcontainer.invokeFlushAfterService to false
java.lang.IllegalStateException: Response is committed