初学struts2 出现There is no Action mapped for namespace...错误

运行环境

 windows8.1

eclipse luna 4.4.2

jre 1.8

struts- 2.4.24

运行项目出现There is no Action mapped for namespace ...如下

HTTP Status 404 - There is no Action mapped for namespace [/user] and action name [userAction!toLogin] associated with context path [/Struts2_11].

type Status report
message There is no Action mapped for namespace [/user] and action name [userAction!toLogin] associated with context path [/Struts2_11].
description The requested resource is not available.

Apache Tomcat/8.0.23

一般情况下出现这种错误，原因有：

1：struts.xml文件路径错误

2：struts.xml文件内容配置有误

但这两种我都没写错，如下



最后把struts版本换成 struts-2.3.15问题解决。