ERROR org.apache.struts2.dispatcher.Dispatcher - Could not find action or result

struts2中报错：

ERROR org.apache.struts2.dispatcher.Dispatcher - Could not find action or result
/testtag/

com.opensymphony.xwork2.config.ConfigurationException: There is no Action mapped for namespace [/] and action name [] associated with context path [/testtag].
at com.opensymphony.xwork2.DefaultActionProxy.prepare(DefaultActionProxy.java:185) ~[xwork-core-2.3.32.jar:2.3.32]
at org.apache.struts2.impl.StrutsActionProxy.prepare(StrutsActionProxy.java:63) ~[struts2-core-2.3.32.jar:2.3.32]
at org.apache.struts2.impl.StrutsActionProxyFactory.createActionProxy(StrutsActionProxyFactory.java:37) ~[struts2-core-2.3.32.jar:2.3.32]
at com.opensymphony.xwork2.DefaultActionProxyFactory.createActionProxy(DefaultActionProxyFactory.java:58) ~[xwork-core-2.3.32.jar:2.3.32]
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:565) [struts2-core-2.3.32.jar:2.3.32]
at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:81) [struts2-core-2.3.32.jar:2.3.32]
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:99) [struts2-core-2.3.32.jar:2.3.32]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [catalina.jar:8.5.32]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [catalina.jar:8.5.32]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) [catalina.jar:8.5.32]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [catalina.jar:8.5.32]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:493) [catalina.jar:8.5.32]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [catalina.jar:8.5.32]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) [catalina.jar:8.5.32]
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:650) [catalina.jar:8.5.32]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [catalina.jar:8.5.32]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) [catalina.jar:8.5.32]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:800) [tomcat-coyote.jar:8.5.32]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-coyote.jar:8.5.32]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:800) [tomcat-coyote.jar:8.5.32] at org.apache.tomcat.util.net.NioEndpoint$ConnectionHandler.process(AbstractProtocol.java:800)[tomcat−coyote.jar:8.5.32]atorg.apache.tomcat.util.net.NioEndpointSocketProcessor.doRun(NioEndpoint.java:1471) [tomcat-coyote.jar:8.5.32]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-coyote.jar:8.5.32]
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [?:1.8.0_121]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [?:1.8.0_121] at org.apache.tomcat.util.threads.TaskThread$Worker.run(UnknownSource)[?:1.8.01​21]atorg.apache.tomcat.util.threads.TaskThreadWrappingRunnable.run(TaskThread.java:61) [tomcat-util.jar:8.5.32]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_121]

解决方案：

没有初始界面，在没有输入action的时候报错，输入action的时候可以正确运行。

可以再WebContent中加入一个初始界面（index.jsp）。错误就没了。