The Ajax return value reports an error, and the spring boot development Ajax return value reports an error

org.thymeleaf.exceptions.TemplateInputException: Error resolving template “succeed”, template might not exist or might not be accessible by any of the configured Template Resolvers
at org.thymeleaf.engine.TemplateManager.resolveTemplate(TemplateManager.java:870) ~[thymeleaf-3.0.9.RELEASE.jar:3.0.9.RELEASE]
at org.thymeleaf.engine.TemplateManager.parseAndProcess(TemplateManager.java:607) ~[thymeleaf-3.0.9.RELEASE.jar:3.0.9.RELEASE]
at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1098) ~[thymeleaf-3.0.9.RELEASE.jar:3.0.9.RELEASE]
at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1072) ~[thymeleaf-3.0.9.RELEASE.jar:3.0.9.RELEASE]
at org.thymeleaf.spring5.view.ThymeleafView.renderFragment(ThymeleafView.java:354) ~[thymeleaf-spring5-3.0.9.RELEASE.jar:3.0.9.RELEASE]
at org.thymeleaf.spring5.view.ThymeleafView.render(ThymeleafView.java:187) ~[thymeleaf-spring5-3.0.9.RELEASE.jar:3.0.9.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1325) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1069) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1008) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974) [spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:877) [spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:661) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851) [spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) [tomcat-embed-websocket-8.5.31.jar:8.5.31]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) [spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:109) [spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:81) [spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) [spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:496) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:790) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1468) [tomcat-embed-core-8.5.31.jar:8.5.31]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-8.5.31.jar:8.5.31]
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [na:1.8.0_172]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [na:1.8.0_172]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.5.31.jar:8.5.31]
at java.lang.Thread.run(Unknown Source) [na:1.8.0_172]


Add the @ResponseBody annotation to the method


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