org.elasticsearch.ElasticsearchStatusException: Elasticsearch exception [type=index_not_found_exception, reason=no such index [People]]
	at org.elasticsearch.rest.BytesRestResponse.errorFromXContent(BytesRestResponse.java:178) ~[elasticsearch-7.17.4.jar:7.17.4]
	at org.elasticsearch.client.RestHighLevelClient.parseEntity(RestHighLevelClient.java:2484) ~[elasticsearch-rest-high-level-client-7.17.4.jar:7.17.4]
	at org.elasticsearch.client.RestHighLevelClient.parseResponseException(RestHighLevelClient.java:2461) ~[elasticsearch-rest-high-level-client-7.17.4.jar:7.17.4]
	at org.elasticsearch.client.RestHighLevelClient.internalPerformRequest(RestHighLevelClient.java:2184) ~[elasticsearch-rest-high-level-client-7.17.4.jar:7.17.4]
	at org.elasticsearch.client.RestHighLevelClient.performRequest(RestHighLevelClient.java:2137) ~[elasticsearch-rest-high-level-client-7.17.4.jar:7.17.4]
	at org.elasticsearch.client.RestHighLevelClient.performRequestAndParseEntity(RestHighLevelClient.java:2105) ~[elasticsearch-rest-high-level-client-7.17.4.jar:7.17.4]
	at org.elasticsearch.client.RestHighLevelClient.search(RestHighLevelClient.java:1367) ~[elasticsearch-rest-high-level-client-7.17.4.jar:7.17.4]
	at org.springframework.data.elasticsearch.core.ElasticsearchRestTemplate.lambda$count$13(ElasticsearchRestTemplate.java:393) ~[spring-data-elasticsearch-4.4.1.jar:4.4.1]
	at org.springframework.data.elasticsearch.core.ElasticsearchRestTemplate.execute(ElasticsearchRestTemplate.java:582) ~[spring-data-elasticsearch-4.4.1.jar:4.4.1]
	at org.springframework.data.elasticsearch.core.ElasticsearchRestTemplate.count(ElasticsearchRestTemplate.java:393) ~[spring-data-elasticsearch-4.4.1.jar:4.4.1]
	at org.springframework.data.elasticsearch.repository.query.ElasticsearchPartQuery.execute(ElasticsearchPartQuery.java:113) ~[spring-data-elasticsearch-4.4.1.jar:4.4.1]
	at org.springframework.data.repository.core.support.RepositoryMethodInvoker.doInvoke(RepositoryMethodInvoker.java:137) ~[spring-data-commons-2.7.1.jar:2.7.1]
	at org.springframework.data.repository.core.support.RepositoryMethodInvoker.invoke(RepositoryMethodInvoker.java:121) ~[spring-data-commons-2.7.1.jar:2.7.1]
	at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.doInvoke(QueryExecutorMethodInterceptor.java:160) ~[spring-data-commons-2.7.1.jar:2.7.1]
	at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.invoke(QueryExecutorMethodInterceptor.java:139) ~[spring-data-commons-2.7.1.jar:2.7.1]
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.21.jar:5.3.21]
	at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:97) ~[spring-aop-5.3.21.jar:5.3.21]
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.21.jar:5.3.21]
	at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:215) ~[spring-aop-5.3.21.jar:5.3.21]
	at com.sun.proxy.$Proxy62.findByNameAndAge(Unknown Source) ~[na:na]
	at com.example.pgdemo.web.TestController.test(TestController.java:26) ~[main/:na]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_371]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_371]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_371]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_371]
	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) ~[spring-web-5.3.21.jar:5.3.21]
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:150) ~[spring-web-5.3.21.jar:5.3.21]
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:117) ~[spring-webmvc-5.3.21.jar:5.3.21]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895) ~[spring-webmvc-5.3.21.jar:5.3.21]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) ~[spring-webmvc-5.3.21.jar:5.3.21]
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.3.21.jar:5.3.21]
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1067) ~[spring-webmvc-5.3.21.jar:5.3.21]
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963) ~[spring-webmvc-5.3.21.jar:5.3.21]
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.21.jar:5.3.21]
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.3.21.jar:5.3.21]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:655) ~[tomcat-embed-core-9.0.64.jar:4.0.FR]
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.3.21.jar:5.3.21]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) ~[tomcat-embed-core-9.0.64.jar:4.0.FR]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.64.jar:9.0.64]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.3.21.jar:5.3.21]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.21.jar:5.3.21]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
	at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.3.21.jar:5.3.21]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.21.jar:5.3.21]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.3.21.jar:5.3.21]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.21.jar:5.3.21]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197) ~[tomcat-embed-core-9.0.64.jar:9.0.64]
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) [tomcat-embed-core-9.0.64.jar:9.0.64]
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) [tomcat-embed-core-9.0.64.jar:9.0.64]
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135) [tomcat-embed-core-9.0.64.jar:9.0.64]
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.64.jar:9.0.64]
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) [tomcat-embed-core-9.0.64.jar:9.0.64]
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:360) [tomcat-embed-core-9.0.64.jar:9.0.64]
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:399) [tomcat-embed-core-9.0.64.jar:9.0.64]
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.64.jar:9.0.64]
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:890) [tomcat-embed-core-9.0.64.jar:9.0.64]
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1787) [tomcat-embed-core-9.0.64.jar:9.0.64]
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.64.jar:9.0.64]
	at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) [tomcat-embed-core-9.0.64.jar:9.0.64]
	at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) [tomcat-embed-core-9.0.64.jar:9.0.64]
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.64.jar:9.0.64]
	at java.lang.Thread.run(Thread.java:750) [na:1.8.0_371]
	Suppressed: org.elasticsearch.client.ResponseException: method [POST], host [http://127.0.0.1:9200], URI [/People/_search?typed_keys=true&max_concurrent_shard_requests=5&search_type=query_then_fetch&batched_reduce_size=512], status line [HTTP/1.1 404 Not Found]
{"error":{"root_cause":[{"type":"index_not_found_exception","reason":"no such index [People]","resource.type":"index_or_alias","resource.id":"People","index_uuid":"_na_","index":"People"}],"type":"index_not_found_exception","reason":"no such index [People]","resource.type":"index_or_alias","resource.id":"People","index_uuid":"_na_","index":"People"},"status":404}
		

 1.代码运行出现找不到Index，先排除index是否存在。

  2.springboot和ES映射，默认是把对象类型映射为index，class对象默认是大写开头，所以要看是都是因为大小写不匹配。如若因为大小写原因导致，可以通过@Document注解指定index