FreeMarker template error (HTML_DEBUG mode; use RETHROW in production!)

The following has evaluated to null or missing:
==> board_name  [in template "WEB-INF/templates/mobileweb/v1/bbsList.ftl" at line 14, column 38]

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Tip: If the failing expression is known to legally refer to something that's sometimes null or missing, either specify a default value like myOptionalVar!myDefault, or use <#if myOptionalVar??>when-present<#else>when-missing</#if>. (These only cover the last step of the expression; to cover the whole expression, use parenthesis: (myOptionalVar.foo)!myDefault, (myOptionalVar.foo)??
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FTL stack trace ("~" means nesting-related):
	- Failed at: ${board_name}  [in template "WEB-INF/templates/mobileweb/v1/bbsList.ftl" at line 14, column 36]
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Java stack trace (for programmers):
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freemarker.core.InvalidReferenceException: [... Exception message was already printed; see it above ...]
	at freemarker.core.InvalidReferenceException.getInstance(InvalidReferenceException.java:134)
	at freemarker.core.EvalUtil.coerceModelToTextualCommon(EvalUtil.java:481)
	at freemarker.core.EvalUtil.coerceModelToStringOrMarkup(EvalUtil.java:401)
	at freemarker.core.EvalUtil.coerceModelToStringOrMarkup(EvalUtil.java:370)
	at freemarker.core.DollarVariable.calculateInterpolatedStringOrMarkup(DollarVariable.java:100)
	at freemarker.core.DollarVariable.accept(DollarVariable.java:63)
	at freemarker.core.Environment.visit(Environment.java:347)
	at freemarker.core.Environment.visit(Environment.java:353)
	at freemarker.core.Environment.process(Environment.java:326)
	at freemarker.template.Template.process(Template.java:383)
	at org.apache.struts2.views.freemarker.FreemarkerResult.doExecute(FreemarkerResult.java:184)
	at org.apache.struts2.result.StrutsResultSupport.execute(StrutsResultSupport.java:206)
	at com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:375)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:279)
	at com.dsg.fx.freemarker.interceptors.FreeMarkerInterceptor.intercept(FreeMarkerInterceptor.java:446)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:140)
	at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:99)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:201)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:243)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:175)
	at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:99)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:167)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:196)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
	at org.apache.struts2.factory.StrutsActionProxy.execute(StrutsActionProxy.java:48)
	at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:574)
	at org.apache.struts2.dispatcher.ExecuteOperations.executeAction(ExecuteOperations.java:79)
	at org.apache.struts2.dispatcher.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:141)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:142)
	at org.tuckey.web.filters.urlrewrite.RuleChain.handleRewrite(RuleChain.java:176)
	at org.tuckey.web.filters.urlrewrite.RuleChain.doRules(RuleChain.java:145)
	at org.tuckey.web.filters.urlrewrite.UrlRewriter.processRequest(UrlRewriter.java:92)
	at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:394)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:142)
	at org.apache.catalina.filters.HttpHeaderSecurityFilter.doFilter(HttpHeaderSecurityFilter.java:129)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:142)
	at org.apache.catalina.filters.CorsFilter.handleNonCORS(CorsFilter.java:334)
	at org.apache.catalina.filters.CorsFilter.doFilter(CorsFilter.java:161)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:142)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:166)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:88)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:481)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:83)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:643)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:72)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:344)
	at org.apache.coyote.ajp.AjpProcessor.service(AjpProcessor.java:429)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:63)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:935)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1831)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52)
	at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:973)
	at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:491)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:63)
	at java.base/java.lang.Thread.run(Thread.java:1474)