org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping': Invocation of init method failed; nested exception is java.lang.IllegalStateException: Ambiguous mapping. Cannot map 'testingController' method public java.lang.String com.dreainno.mvc.TestingController.showForm() to { /showForm}: There is already 'helloWorldController' bean method public java.lang.String com.dreainno.mvc.HelloWorldController.showForm() mapped.

Error:-

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping': Invocation of init method failed; nested exception is java.lang.IllegalStateException: Ambiguous mapping. Cannot map 'testingController' method 
public java.lang.String com.dreainno.mvc.TestingController.showForm()
to { /showForm}: There is already 'helloWorldController' bean method
public java.lang.String com.dreainno.mvc.HelloWorldController.showForm() mapped.
 org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1778)
 org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:593)
 org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515)
 org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320)
 org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
 org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318)
 org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199)
 org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:845)
 org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:877)
 org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549)
 org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:701)
 org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:667)
 org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:715)
 org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:590)
 org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:529)
 org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:169)
 javax.servlet.GenericServlet.init(GenericServlet.java:158)
 org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490)
 org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
 org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:668)
 org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
 org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408)
 org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
 org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:834)
 org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1415)
 org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
 java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
 java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
 org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
 java.lang.Thread.run(Unknown Source)

Solution:-

This error will occurred when the same mapping caught by spring controller to more than on method throughtout application.

In This sitution you have to given request mapping to controller and when calling method append controller mapping also.

In simple words you have two methods in different controller and you have the mention controller mapping in url

For example

<form action="hello/processFormVersion3" method="post">

In above example hello is controller request mapping parameter and processFormVersion3 is the methods request mapping