Spring Boot 项目，在 Spring Tool Suite 4, Version: 4.4.0.RELEASE 运行没有问题，将项目中的静态资源和页面复制到 IDEA 的项目中，除了 IDE 不同，其他基本相同。
运行 IDEA 中的项目，然后访问，出现异常：
Exception processing template "index": An error happened during template parsing (template: "class path resource [templates/index.html]")
具体异常：
1 2019-12-10 21:37:40.896 ERROR 10276 --- [nio-8081-exec-1] org.thymeleaf.TemplateEngine : [THYMELEAF][http-nio-8081-exec-1] Exception processing template "index": An error happened during template parsing (template: "class path resource [templates/index.html]") 2 3 org.thymeleaf.exceptions.TemplateInputException: An error happened during template parsing (template: "class path resource [templates/index.html]") 4 at org.thymeleaf.templateparser.markup.AbstractMarkupTemplateParser.parse(AbstractMarkupTemplateParser.java:241) 5 at org.thymeleaf.templateparser.markup.AbstractMarkupTemplateParser.parseStandalone(AbstractMarkupTemplateParser.java:100) 6 at org.thymeleaf.engine.TemplateManager.parseAndProcess(TemplateManager.java:666) 7 at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1098) 8 at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1072) 9 at org.thymeleaf.spring5.view.ThymeleafView.renderFragment(ThymeleafView.java:362) 10 at org.thymeleaf.spring5.view.ThymeleafView.render(ThymeleafView.java:189) 11 at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1373) 12 at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1118) 13 at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1057) 14 at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) 15 at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) 16 at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) 17 at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) 18 at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) 19 at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) 20 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) 21 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) 22 at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) 23 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) 24 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) 25 at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) 26 at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) 27 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) 28 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) 29 at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) 30 at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) 31 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) 32 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) 33 at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) 34 at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) 35 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) 36 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) 37 at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) 38 at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) 39 at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:526) 40 at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) 41 at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) 42 at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) 43 at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) 44 at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:367) 45 at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) 46 at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:860) 47 at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1591) 48 at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) 49 at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) 50 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) 51 at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) 52 at java.lang.Thread.run(Thread.java:748) 53 Caused by: org.attoparser.ParseException: Error resolving template [_fragment], template might not exist or might not be accessible by any of the configured Template Resolvers (template: "index" - line 3, col 11) 54 at org.attoparser.MarkupParser.parseDocument(MarkupParser.java:393) 55 at org.attoparser.MarkupParser.parse(MarkupParser.java:257) 56 at org.thymeleaf.templateparser.markup.AbstractMarkupTemplateParser.parse(AbstractMarkupTemplateParser.java:230) 57 ... 48 common frames omitted 58 Caused by: org.thymeleaf.exceptions.TemplateInputException: Error resolving template [_fragment], template might not exist or might not be accessible by any of the configured Template Resolvers (template: "index" - line 3, col 11) 59 at org.thymeleaf.engine.TemplateManager.resolveTemplate(TemplateManager.java:869) 60 at org.thymeleaf.engine.TemplateManager.parseStandalone(TemplateManager.java:250) 61 at org.thymeleaf.standard.expression.FragmentExpression.resolveExecutedFragmentExpression(FragmentExpression.java:588) 62 at org.thymeleaf.standard.processor.AbstractStandardFragmentInsertionTagProcessor.computeFragment(AbstractStandardFragmentInsertionTagProcessor.java:379) 63 at org.thymeleaf.standard.processor.AbstractStandardFragmentInsertionTagProcessor.doProcess(AbstractStandardFragmentInsertionTagProcessor.java:110) 64 at org.thymeleaf.processor.element.AbstractAttributeTagProcessor.doProcess(AbstractAttributeTagProcessor.java:74) 65 at org.thymeleaf.processor.element.AbstractElementTagProcessor.process(AbstractElementTagProcessor.java:95) 66 at org.thymeleaf.util.ProcessorConfigurationUtils$ElementTagProcessorWrapper.process(ProcessorConfigurationUtils.java:633) 67 at org.thymeleaf.engine.ProcessorTemplateHandler.handleOpenElement(ProcessorTemplateHandler.java:1314) 68 at org.thymeleaf.engine.TemplateHandlerAdapterMarkupHandler.handleOpenElementEnd(TemplateHandlerAdapterMarkupHandler.java:304) 69 at org.thymeleaf.templateparser.markup.InlinedOutputExpressionMarkupHandler$InlineMarkupAdapterPreProcessorHandler.handleOpenElementEnd(InlinedOutputExpressionMarkupHandler.java:278) 70 at org.thymeleaf.standard.inline.OutputExpressionInlinePreProcessorHandler.handleOpenElementEnd(OutputExpressionInlinePreProcessorHandler.java:186) 71 at org.thymeleaf.templateparser.markup.InlinedOutputExpressionMarkupHandler.handleOpenElementEnd(InlinedOutputExpressionMarkupHandler.java:124) 72 at org.attoparser.HtmlElement.handleOpenElementEnd(HtmlElement.java:109) 73 at org.attoparser.HtmlMarkupHandler.handleOpenElementEnd(HtmlMarkupHandler.java:297) 74 at org.attoparser.MarkupEventProcessorHandler.handleOpenElementEnd(MarkupEventProcessorHandler.java:402) 75 at org.attoparser.ParsingElementMarkupUtil.parseOpenElement(ParsingElementMarkupUtil.java:159) 76 at org.attoparser.MarkupParser.parseBuffer(MarkupParser.java:710) 77 at org.attoparser.MarkupParser.parseDocument(MarkupParser.java:301) 78 ... 50 common frames omitted 79 80 2019-12-10 21:37:40.900 ERROR 10276 --- [nio-8081-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.thymeleaf.exceptions.TemplateInputException: An error happened during template parsing (template: "class path resource [templates/index.html]")] with root cause 81 82 org.thymeleaf.exceptions.TemplateInputException: Error resolving template [_fragment], template might not exist or might not be accessible by any of the configured Template Resolvers (template: "index" - line 3, col 11) 83 at org.thymeleaf.engine.TemplateManager.resolveTemplate(TemplateManager.java:869) 84 at org.thymeleaf.engine.TemplateManager.parseStandalone(TemplateManager.java:250) 85 at org.thymeleaf.standard.expression.FragmentExpression.resolveExecutedFragmentExpression(FragmentExpression.java:588) 86 at org.thymeleaf.standard.processor.AbstractStandardFragmentInsertionTagProcessor.computeFragment(AbstractStandardFragmentInsertionTagProcessor.java:379) 87 at org.thymeleaf.standard.processor.AbstractStandardFragmentInsertionTagProcessor.doProcess(AbstractStandardFragmentInsertionTagProcessor.java:110) 88 at org.thymeleaf.processor.element.AbstractAttributeTagProcessor.doProcess(AbstractAttributeTagProcessor.java:74) 89 at org.thymeleaf.processor.element.AbstractElementTagProcessor.process(AbstractElementTagProcessor.java:95) 90 at org.thymeleaf.util.ProcessorConfigurationUtils$ElementTagProcessorWrapper.process(ProcessorConfigurationUtils.java:633) 91 at org.thymeleaf.engine.ProcessorTemplateHandler.handleOpenElement(ProcessorTemplateHandler.java:1314) 92 at org.thymeleaf.engine.TemplateHandlerAdapterMarkupHandler.handleOpenElementEnd(TemplateHandlerAdapterMarkupHandler.java:304) 93 at org.thymeleaf.templateparser.markup.InlinedOutputExpressionMarkupHandler$InlineMarkupAdapterPreProcessorHandler.handleOpenElementEnd(InlinedOutputExpressionMarkupHandler.java:278) 94 at org.thymeleaf.standard.inline.OutputExpressionInlinePreProcessorHandler.handleOpenElementEnd(OutputExpressionInlinePreProcessorHandler.java:186) 95 at org.thymeleaf.templateparser.markup.InlinedOutputExpressionMarkupHandler.handleOpenElementEnd(InlinedOutputExpressionMarkupHandler.java:124) 96 at org.attoparser.HtmlElement.handleOpenElementEnd(HtmlElement.java:109) 97 at org.attoparser.HtmlMarkupHandler.handleOpenElementEnd(HtmlMarkupHandler.java:297) 98 at org.attoparser.MarkupEventProcessorHandler.handleOpenElementEnd(MarkupEventProcessorHandler.java:402) 99 at org.attoparser.ParsingElementMarkupUtil.parseOpenElement(ParsingElementMarkupUtil.java:159) 100 at org.attoparser.MarkupParser.parseBuffer(MarkupParser.java:710) 101 at org.attoparser.MarkupParser.parseDocument(MarkupParser.java:301) 102 at org.attoparser.MarkupParser.parse(MarkupParser.java:257) 103 at org.thymeleaf.templateparser.markup.AbstractMarkupTemplateParser.parse(AbstractMarkupTemplateParser.java:230) 104 at org.thymeleaf.templateparser.markup.AbstractMarkupTemplateParser.parseStandalone(AbstractMarkupTemplateParser.java:100) 105 at org.thymeleaf.engine.TemplateManager.parseAndProcess(TemplateManager.java:666) 106 at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1098) 107 at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1072) 108 at org.thymeleaf.spring5.view.ThymeleafView.renderFragment(ThymeleafView.java:362) 109 at org.thymeleaf.spring5.view.ThymeleafView.render(ThymeleafView.java:189) 110 at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1373) 111 at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1118) 112 at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1057) 113 at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) 114 at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) 115 at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) 116 at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) 117 at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) 118 at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) 119 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) 120 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) 121 at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) 122 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) 123 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) 124 at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) 125 at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) 126 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) 127 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) 128 at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) 129 at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) 130 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) 131 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) 132 at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) 133 at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) 134 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) 135 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) 136 at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) 137 at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) 138 at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:526) 139 at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) 140 at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) 141 at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) 142 at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) 143 at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:367) 144 at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) 145 at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:860) 146 at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1591) 147 at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) 148 at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) 149 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) 150 at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) 151 at java.lang.Thread.run(Thread.java:748)
起初是直接运行项目，即 Shift F10：
![Thymeleaf 异常：Exception processing template "index&a](https://image.shishitao.com:8440/aHR0cHM6Ly93d3cuam13d3cubmV0L3VwbG9hZHMvYWxsaW1nLzIwMjAvMi9KSnJNSm4ucG5n.png?w=700&webp=1 "Thymeleaf 异常：Exception processing template "index&a")
后来重新编译项目，再访问，就没有出现异常：
![Thymeleaf 异常：Exception processing template "index&a](https://image.shishitao.com:8440/aHR0cHM6Ly93d3cuam13d3cubmV0L3VwbG9hZHMvYWxsaW1nLzIwMjAvMi9BckUzeXkucG5n.png?w=700&webp=1 "Thymeleaf 异常：Exception processing template "index&a")