Custom Report (Advanced) Error: ReportDefinition cannot be loaded

An error has occurred!
The following error happened somewhere on this page:
javax.servlet.jsp.JspException: java.lang.IllegalArgumentException: Type org.openmrs.module.reporting.report.ReportDefinition cannot be loaded

(The full error stack trace output is in the source of this page.)

<!--
javax.servlet.jsp.JspException: java.lang.IllegalArgumentException: Type org.openmrs.module.reporting.report.ReportDefinition cannot be loaded
	at org.apache.taglibs.standard.tag.common.core.ImportSupport.acquireString(Unknown Source)
	at org.apache.taglibs.standard.tag.common.core.ImportSupport.doEndTag(Unknown Source)
	at org.openmrs.web.taglib.PortletTag.doEndTag(PortletTag.java:115)
	at org.apache.jsp.WEB_002dINF.view.module.reporting.reports.reportEditor_jsp._jspx_meth_openmrs_005fportlet_005f0(reportEditor_jsp.java:3940)
	at org.apache.jsp.WEB_002dINF.view.module.reporting.reports.reportEditor_jsp._jspx_meth_c_005fwhen_005f4(reportEditor_jsp.java:3903)
	at org.apache.jsp.WEB_002dINF.view.module.reporting.reports.reportEditor_jsp._jspx_meth_c_005fchoose_005f4(reportEditor_jsp.java:3863)
	at org.apache.jsp.WEB_002dINF.view.module.reporting.reports.reportEditor_jsp._jspService(reportEditor_jsp.java:603)
	at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
	at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
	at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
	at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:70)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:70)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:646)
	at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:436)
	at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:374)
	at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:302)
	at org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:236)
	at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:257)
	at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1183)
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:902)
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:807)
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:571)
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:501)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.openmrs.module.web.filter.ModuleFilterChain.doFilter(ModuleFilterChain.java:76)
	at org.openmrs.module.web.filter.ModuleFilter.doFilter(ModuleFilter.java:58)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.openmrs.web.filter.OpenmrsFilter.doFilterInternal(OpenmrsFilter.java:112)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:198)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.openmrs.web.filter.StartupFilter.doFilter(StartupFilter.java:82)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.openmrs.web.filter.StartupFilter.doFilter(StartupFilter.java:82)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.openmrs.web.filter.StartupFilter.doFilter(StartupFilter.java:82)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:96)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
	at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:859)
	at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:574)
	at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1527)
	at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.IllegalArgumentException: Type org.openmrs.module.reporting.report.ReportDefinition cannot be loaded
	at org.openmrs.module.reporting.web.controller.portlet.ParameterizablePortletController.populateModel(ParameterizablePortletController.java:36)
	at org.openmrs.web.controller.PortletController.handleRequest(PortletController.java:419)
	at org.openmrs.module.reporting.web.controller.portlet.ReportingPortletController.handleRequest(ReportingPortletController.java:36)
	at org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter.handle(SimpleControllerHandlerAdapter.java:48)
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:875)
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:807)
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:571)
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:501)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:70)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:646)
	at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:551)
	at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:488)
	... 71 more
Caused by: java.lang.ClassNotFoundException: org.openmrs.module.reporting.report.ReportDefinition
	at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1387)
	at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1233)
	at org.openmrs.util.OpenmrsClassLoader.loadClass(OpenmrsClassLoader.java:126)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
	at org.openmrs.api.context.Context.loadClass(Context.java:184)
	at org.openmrs.module.reporting.web.controller.portlet.ParameterizablePortletController.populateModel(ParameterizablePortletController.java:32)
	... 88 more
-->