I am working on adding functionality download functionality to a Java app using JSP and Struts 1.2.9 for UI.
Basically, I am fetching a list of data from the DB and then generate a CSV file from the data.
Currently, I have mapped a new UI button to a new Struts action. The download action class does the following:

public class DownloadCSVAction extends AbstractAction {

    public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception{
    // some code to fetch the content
    response.setContentType("text/csv");

    DateFormat format = new SimpleDateFormat("yyyy-MM-dd_HH-mm-ss");
    String currentTime = format.format(new Date());
    String headerKey = "Content-Disposition";
    String headerValue = "attachment; filename=report_" + currentTime + ".csv";
    response.setHeader(headerKey, headerValue);

    PrintWriter printWriter = response.getWriter();
    
    // some code to put content in CSV string format
    printWriter.close();

    // Unsetting Content-Disposition header to remove file download from the response after download
    response.setContentType("text/html");
    response.setHeader(headerKey, "");

    return mapping.findForward("success");
  }    
}

Now this code is downloading the file just fine. However, once the file is downloaded, anything else I click in the UI results in an error

12:14:37,216 ERROR [io.undertow.request] (default task-13) UT005023: Exception handling request to /SecurityLibrary/DownloadCSVInit.do: java.lang.IllegalStateException: UT010019: Response already commited
    at io.undertow.servlet.spec.ServletOutputStreamImpl.resetBuffer(ServletOutputStreamImpl.java:732)
    at io.undertow.servlet.spec.HttpServletResponseImpl.resetBuffer(HttpServletResponseImpl.java:495)
    at io.undertow.servlet.spec.RequestDispatcherImpl.forwardImpl(RequestDispatcherImpl.java:167)
    at io.undertow.servlet.spec.RequestDispatcherImpl.forwardImplSetup(RequestDispatcherImpl.java:147)
    at io.undertow.servlet.spec.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:111)
    at org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1085)
    at ...MainRequestProcessor.processForwardConfig(MainRequestProcessor.java:345)
    at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:241)
    at ...MainRequestProcessor.process(MainRequestProcessor.java:78)
    at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
    at ...MainServlet.process(MainServlet.java:101)
    at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
    at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:85)
    at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:62)
    at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
    at org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:78)
    at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:131)
    at io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:57)
    at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:46)
    at io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:64)
    at io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:60)
    at io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:77)
    at io.undertow.security.handlers.NotificationReceiverHandler.handleRequest(NotificationReceiverHandler.java:50)
    at io.undertow.security.handlers.AbstractSecurityContextAssociationHandler.handleRequest(AbstractSecurityContextAssociationHandler.java:43)
    at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at org.wildfly.extension.undertow.security.jacc.JACCContextIdHandler.handleRequest(JACCContextIdHandler.java:61)
    at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at org.wildfly.extension.undertow.deployment.GlobalRequestControllerHandler.handleRequest(GlobalRequestControllerHandler.java:68)
    at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:292)
    at io.undertow.servlet.handlers.ServletInitialHandler.access$100(ServletInitialHandler.java:81)
    at io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:138)
    at io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:135)
    at io.undertow.servlet.core.ServletRequestContextThreadSetupAction$1.call(ServletRequestContextThreadSetupAction.java:48)
    at io.undertow.servlet.core.ContextClassLoaderSetupAction$1.call(ContextClassLoaderSetupAction.java:43)
    at org.wildfly.extension.undertow.security.SecurityContextThreadSetupAction.lambda$create$0(SecurityContextThreadSetupAction.java:105)
    at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1508)
    at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1508)
    at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1508)
    at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1508)
    at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:272)
    at io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:81)
    at io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:104)
    at io.undertow.server.Connectors.executeRootHandler(Connectors.java:326)
    at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:812)

I tried solving my issue using:

• Error : IllegalStateException in Java. Cannot forward after response has been committed
• after download a image ,i want to redirect on another page, but not able to
• https://www.javatpoint.com/downloading-file-from-the-server-in-jsp

but nothing helped.