WCEM:clicking on custom button(Excel Downlaod) giving message "An error occurred; please try again. If the error persists, please contact technical support."

Question

Hi Expert,
I need help.
I created a custom button to download data to an excel sheet. after clicking the button I am getting message
"An error occurred; please try again. If the error persists, please contact technical support.".
I tried debugging WCEM, but it is not even reaching that point.
Your help will be highly appreciated.
here is the code.
BitContentview.XHTML
<wec:commandButton  id="bdtexcel" immediate="true" actionListener="#{cc.vch.DownloadBITData}" type="submit" value="#{i18n['invoices.ui.openitems.printSelected']}"/>
UI-repository.xml
  <ViewComponent name="BITContentView"  componentHandlerClassName="com.cpr.cprwec.app.comm.module.ebpp.ui.handler.impl.BITDetailViewVCHandler"/>
BITDetailViewVCHnadler.java
package com.cpr.cprwec.app.comm.module.ebpp.ui.handler.impl;
import com.cpr.cprwec.app.comm.module.ebpp.backendobject.interf.EbppBackend;
import java.io.IOException;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;
import javax.faces.context.FacesContext;
import javax.faces.context.FacesContext;
import javax.faces.event.ActionEvent;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import com.cpr.cprwec.app.comm.module.ebpp.modulemgmt.impl.EbppModuleAccessImpl;
import com.cpr.cprwec.app.comm.module.ebpp.modulemgmt.interf.EbppModuleAccess;
import com.cpr.cprwec.app.comm.module.ebpp.ui.dto.impl.DisputeDataDTOImpl;
import com.cpr.cprwec.app.comm.module.ebpp.ui.dto.impl.OpenItemDTOImpl;
import com.cpr.cprwec.app.comm.module.ebpp.ui.dto.interf.DisputeDataDTO;
import com.cpr.cprwec.app.comm.module.ebpp.ui.dto.interf.OpenItemDTO;
import com.cpr.cprwec.app.comm.module.ebpp.ui.dto.impl.BITDataDTOImpl;
import com.cpr.cprwec.app.comm.module.ebpp.ui.dto.interf.BITDataDTO;
import com.cpr.cprwec.app.comm.module.ebpp.ui.dto.impl.BITDetailDTOImpl;
import com.cpr.cprwec.app.comm.module.ebpp.ui.dto.interf.BITDetailDTO;
import com.sap.wec.app.common.module.common.attachment.businessobject.interf.Attachment;
import com.sap.wec.tc.core.backend.sp.jco.JCoConnection;
import com.sap.wec.tc.core.businessobject.BusinessObjectException;
import com.sap.wec.tc.core.common.exceptions.ApplicationBaseRuntimeException;
import com.sap.wec.tc.core.common.logging.WCFLocation;
import com.sap.wec.tc.core.common.searching.businessobject.impl.GenericSearch;
import com.sap.wec.tc.core.common.searching.businessobject.interf.GenericSearchReturnResultData;
import com.sap.wec.tc.core.common.util.GenericFactory;
import com.sap.wec.tc.core.common.util.Message;
import com.sap.wec.tc.core.common.util.MessageList;
import com.sap.wec.tc.core.common.util.table.Table;
import com.sap.wec.tc.core.common.util.table.TableRow;
import com.sap.wec.tc.core.modulemgmt.ForeignModuleAccess;
import com.sap.wec.tc.core.modulemgmt.ModuleAccess;
import com.sap.wec.tc.core.modulemgmt.exceptions.ModuleInactiveException;
import com.sap.wec.tc.core.modulemgmt.exceptions.ModuleLifecycleException;
import com.sap.wec.tc.core.runtime.WecFrameworkRuntime;
import com.sap.wec.tc.core.runtime.WecSession;
import com.sap.wec.tc.core.runtime.jsf.WecFrameworkRuntimeJSF;
import com.sap.wec.tc.core.runtime.jsf.composition.PageManagerBean;
import com.sap.wec.tc.core.runtime.navigation.NavigationCondition;
import com.sap.wec.tc.core.ui.composition.menu.MenuManager;
import com.sap.wec.tc.core.ui.composition.menu.MenuMetadataException;
import com.sap.wec.tc.core.ui.vc.BuildTime;
import com.sap.wec.tc.core.ui.vc.NavigationParameterBinding;
import com.sap.wec.tc.core.ui.vc.RequestParameterBinding;
import com.sap.wec.tc.core.ui.vc.impl.ViewComponentHandlerBaseImpl;
import com.cpr.cprwec.app.comm.module.ebpp.businessobject.interf.BIT;
import com.cpr.cprwec.app.comm.module.ebpp.businessobject.impl.BITImpl;
public class BITDetailViewVCHandler extends
        ViewComponentHandlerBaseImpl<EbppModuleAccess> {
    protected static final WCFLocation LOCATION = WCFLocation
            .getInstance(BITDetailViewVCHandler.class.getName());
    public BITDataDTO bitDataDTO;
    public BITDetailDTO bitDetailDTO;
    public List<BITDataDTO> BITDataDTOList;
    public List<BITDetailDTO> BITDetailDTOList;
    public boolean noBITData;
    public boolean noBITDetail;
    public boolean renderPanel = true;
    public boolean isDownloadBITData;
    public boolean isDownloadBITDetail;
    public boolean downloadStarted=false;
    public boolean BITFound =false;
    public boolean isBITFound() {
        return BITFound;
    public void setDownloadStarted( boolean downloadStarted ){
        this.downloadStarted = downloadStarted;
    public boolean getDownloadStarted(){
        return this.downloadStarted;
    public void setBITFound(boolean BITFound) {
        this.BITFound = BITFound;
    public String getObjectID() {
        return objectID;
    public void setObjectID(String objectID) {
        this.objectID = objectID;
    public List<BITDataDTO> getBITDataDTOList() {
        return BITDataDTOList;
    public List<BITDetailDTO> getBITDetailDTOList() {
        return BITDetailDTOList;
    public Boolean getNoBITData() {
        return noBITData;
    public Boolean getNoBITDetail() {
        return noBITDetail;
    public Boolean getRenderPanel() {
        return renderPanel;
    private static final int DEFAULT_BUFFER_SIZE = 1024000;
    public Attachment attachmentData;
    public Attachment getAttachmentData() {
        return attachmentData;
    @RequestParameterBinding(maxLength = 1024)
    protected String objectID;
    @BuildTime
    public String processBuildTime() throws BusinessObjectException {
        BIT BIT = null;
        noBITData = noBITDetail = false;
        renderPanel = true;
        if (isLoggedIn()) {
            if ( isDownloadBITData == true ){
                this.downloadBITDataExcel();
            else {
            this.getModuleAccess().getBITBO().clearMessages();
            BIT = this.moduleAccess.getBITBO().getBITFromBackend(objectID);
            BITDataDTOList = BIT.getBITDataDTOList();
            BITDetailDTOList = BIT.getBITDetailDTOList();
            MessageList objectData = this.getModuleAccess().getBITBO()
                    .getMessageList();
            if (objectData.size() > 0) {
                noBITData = noBITDetail = true;
                renderPanel = false;
                this.addMessageList(objectData);
        return checkLoginCondition();
    private boolean isLoggedIn() {
        return checkLoginCondition() == null;
    private String checkLoginCondition() {
        NavigationCondition navCondition = getNavigationCondition("login");
        if (!navCondition.isFullfiled()) {
            navCondition.addToNavigationStack();
            return navCondition.getOutcome();
        return null;
    public String downloadBITData(){
        downloadStarted = true;
        isDownloadBITData = true;
        downloadBITDataExcel();
        return checkLoginCondition();
    public void downloadBITDataExcel() {
    //    dummyDebug("downloadBITDataExcel", BITDataDTOList.size(), "", "" );
        if (BITDataDTOList.size() > 0) {
            try {
                attachmentData = this.getModuleAccess().getDownloadBO()
                        .getBITDataExcel(BITDataDTOList);
                if (attachmentData != null) {
                    FacesContext faces = FacesContext.getCurrentInstance();
                    HttpServletResponse response = (HttpServletResponse) faces
                            .getExternalContext().getResponse();
                    response.reset();
                    response.setContentType(attachmentData
                            .getAttachmentMimeType());
                    response.setContentLength(attachmentData
                            .getAttachmentContent().length);
                    response.setHeader("Content-disposition",
                            "attachment;filename="
                                    + attachmentData.getAttachmentName());
                    response.setBufferSize(DEFAULT_BUFFER_SIZE);
                    ServletOutputStream out;
                    try {
                        out = response.getOutputStream();
                        out.write(attachmentData.getAttachmentContent());
                        out.flush();
                        faces.responseComplete();
                    } catch (IOException e) {
                        throw new ApplicationBaseRuntimeException(
                                "Problem opening file", e);
                    } finally {
                        attachmentData = null;
            } catch (BusinessObjectException e) {
                e.printStackTrace();
        isDownloadBITData = false;

Answer 1

Thanks Hamendra for checking the issue.
I am setting up breakpoints in WCEM, tab JAVA EE then from menu RUN->Toggle brekpoints and then debug configuration.
the breakpoints are in several places in  handler class BITDetailviewVCHandler class including method  downloadBITData.
this method I am calling from BitContentview.XHTML
<wec:commandButton  id="bdtexcel" immediate="true" actionListener="#{cc.vch.DownloadBITData}" type="submit" value="#{i18n['invoices.ui.openitems.printSelected']}"/>
When the BIT page is loading the control stops at the breakpoint.
but it is not stopping there  when i click the 'Excel Download' button.
How do I get the log file. I am very new to WCEM, please guide me.
I tried to debug the UI using Google chrome. it is giving me the following error.
POST https://<>/<>/<>/<>HomePage.jsf?wec-appid=<>MAINAPP6&wec-locale=en_US 500 (Internal Server Error)
when I expand the node
c.event.trigger:<>/<>/javax.faces.resource/sap/comp.theme/templates/jquery/lib/jquery-1.4.2.min.js.jsf:54
c.event.trigger:<>/<>/javax.faces.resource/sap/comp.theme/templates/jquery/lib/jquery-1.4.2.min.js.jsf:54
c.event.trigger:<>/<>/javax.faces.resource/sap/comp.theme/templates/jquery/lib/jquery-1.4.2.min.js.jsf:66
(anonymous function):<>/<>/javax.faces.resource/sap/comp.theme/templates/jquery/lib/jquery-1.4.2.min.js.jsf:30
c.extend.each:<>/<>/javax.faces.resource/sap/comp.theme/templates/jquery/lib/jquery-1.4.2.min.js.jsf:24 c.fn.c.each:<>/<>/javax.faces.resource/sap/comp.theme/templates/jquery/lib/jquery-1.4.2.min.js.jsf:66 c.fn.extend.trigger:<>/<>/javax.faces.resource/<>dev/comp.theme/templates/jquery/js/commandButton.js.jsf:31
com.sap.wec.commandButton.submitForm:<>/<>/main/<>HomePage.jsf?wec-appid=<>MAINAPP6&objectID=500000233&page=D61CFFF8E75D48A1B348F315D209EFF9&wec-locale=en_US:48 onclick
Navigated to https://wsapdjd803.<>.ca:<>/<>/main/<>HomePage.jsf?wec-appid=<>MAINAPP6&wec-locale=en_US
Seems to be it is failing somewhere commandButton-related JavaScript functions
Thanks
Subassish