Bom dia! Estou fazendo um código para um trabalho final da disciplina de Banco de dados, one preciso fazer uma aplicação com 3 camadas. Utilizei o mysql(xampp) como database, e, no netbeans, java como back-end e jsp como front-end. Estou utlizando o Tomcat 9, mas quando tento abrir a pagina aparece o seguinte erro: " An Error Occurred: Cannot invoke “javax.faces.view.ViewDeclarationLanguage.calculateResourceLibraryContracts(javax.faces.context.FacesContext, String)” because “vdl” is null ".
java.lang.NullPointerException: Cannot invoke "javax.faces.view.ViewDeclarationLanguage.calculateResourceLibraryContracts(javax.faces.context.FacesContext, String)" because "vdl" is null
at com.sun.faces.application.view.FaceletViewHandlingStrategy.createView(FaceletViewHandlingStrategy.java:333)
at com.sun.faces.application.view.MultiViewHandler.createView(MultiViewHandler.java:176)
at org.apache.struts.faces.application.ViewHandlerImpl.createView(ViewHandlerImpl.java:157)
at com.sun.faces.lifecycle.RestoreViewPhase.execute(RestoreViewPhase.java:261)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:100)
at com.sun.faces.lifecycle.RestoreViewPhase.doPhase(RestoreViewPhase.java:133)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:201)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:670)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:228)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:190)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:163)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:687)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:382)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:893)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1723)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.base/java.lang.Thread.run(Thread.java:831)