ERRO value={itemMB.item.nome_item}: Target Unreachable, item returned null

type Exception report

message /index.xhtml @191,61 value="#{itemMB.item.nome_item}": Target Unreachable, 'item' returned null

description The server encountered an internal error that prevented it from fulfilling this request.

exception

javax.servlet.ServletException: /index.xhtml @191,61 value="#{itemMB.item.nome_item}": Target Unreachable, 'item' returned null
	javax.faces.webapp.FacesServlet.service(FacesServlet.java:606)
	org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
root cause

javax.el.PropertyNotFoundException: /index.xhtml @191,61 value="#{itemMB.item.nome_item}": Target Unreachable, 'item' returned null
	com.sun.faces.facelets.el.TagValueExpression.getType(TagValueExpression.java:100)
	org.primefaces.util.ComponentUtils.getConverter(ComponentUtils.java:146)
	org.primefaces.component.multiselectlistbox.MultiSelectListboxRenderer.encodeListItems(MultiSelectListboxRenderer.java:112)
	org.primefaces.component.multiselectlistbox.MultiSelectListboxRenderer.encodeLists(MultiSelectListboxRenderer.java:101)
	org.primefaces.component.multiselectlistbox.MultiSelectListboxRenderer.encodeMarkup(MultiSelectListboxRenderer.java:71)
	org.primefaces.component.multiselectlistbox.MultiSelectListboxRenderer.encodeEnd(MultiSelectListboxRenderer.java:49)
	javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:875)
	org.primefaces.renderkit.CoreRenderer.renderChild(CoreRenderer.java:89)
	org.primefaces.renderkit.CoreRenderer.renderChildren(CoreRenderer.java:72)
	org.primefaces.component.overlaypanel.OverlayPanelRenderer.encodeMarkup(OverlayPanelRenderer.java:59)
	org.primefaces.component.overlaypanel.OverlayPanelRenderer.encodeEnd(OverlayPanelRenderer.java:37)
	javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:875)
	com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:312)
	com.sun.faces.renderkit.html_basic.GridRenderer.renderRow(GridRenderer.java:185)
	com.sun.faces.renderkit.html_basic.GridRenderer.encodeChildren(GridRenderer.java:129)
	javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:845)
	javax.faces.component.UIComponent.encodeAll(UIComponent.java:1779)
	javax.faces.render.Renderer.encodeChildren(Renderer.java:168)
	javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:845)
	javax.faces.component.UIComponent.encodeAll(UIComponent.java:1779)
	javax.faces.component.UIComponent.encodeAll(UIComponent.java:1782)
	javax.faces.component.UIComponent.encodeAll(UIComponent.java:1782)
	com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:424)
	com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:125)
	com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:121)
	com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
	com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
	javax.faces.webapp.FacesServlet.service(FacesServlet.java:594)
	org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
note The full stack trace of the root cause is available in the Apache Tomcat/7.0.70 logs.

<p:overlayPanel id="selectItemPanel" for="btnOverlayPanel" widgetVar="selectItemPanel"
								hideEffect="fold" showEffect="fold">
								<p:multiSelectListbox value="#{itemMB.item.nome_item}" id="Item"
									required="true" effect="slide" showHeaders="false">
									<f:selectItems value="#{menuMultSelectList.categories}" />
								</p:multiSelectListbox>
								

								<p:commandButton action="#{itemMB.item.trocaIcone}" value="Selecionar"
									icon="ui-icon-cart" onclick="PF('selectItemPanel').hide();"
									process="@form:selectItemPanel" update="itemTexto itemImagem"
									style="float: right; margin-bottom: 10px; margin-right: 10px;
									border-radius: 5px; background: #9be1e1;"/>
							</p:overlayPanel>

							<h:graphicImage id="itemImagem"
								url="resources/images/equipamentos/#{itemMB.item.cod_icone}.png"
								value="#{itemMB.item.cod_icone}" />
							<h:outputText id="itemTexto" value="#{itemMB.item.nome_item}" />

package item;

import java.sql.SQLException;
import java.util.List;

import javax.annotation.PostConstruct;
import javax.faces.application.FacesMessage;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.ManagedProperty;
import javax.faces.bean.SessionScoped;
import javax.faces.context.FacesContext;
import usuario.LoginManagedBean;

@ManagedBean(name = "itemMB")
@SessionScoped
public class ItemManagedBean {
	
	@PostConstruct
	public void init() {
		item.setNome_item("Selecione o item");
		item.setCod_icone("0000000");
		item.setServidor("Arcan");
		
	}

	@ManagedProperty(value = "#", name = "loginMB")
	private LoginManagedBean loginMB;

	public LoginManagedBean getLoginMB() {
		return loginMB;
	}
	public void setLoginMB(LoginManagedBean loginMB) {
		this.loginMB = loginMB;
	}

	Item item = new Item();
	public void cadastraItem() throws SQLException {
		item.setVendedor(loginMB.getUser_id());
		if (loginMB.getUser_id() == null) {
			FacesContext.getCurrentInstance().addMessage(null, new FacesMessage(FacesMessage.SEVERITY_WARN, "Alerta!",
					"Você precisa estar logado para cadastrar itens!"));
		} else {
			ConnectItem con = new ConnectItem();
			if (con.insertItem(item)) {
				FacesContext.getCurrentInstance().addMessage(null,
						new FacesMessage(FacesMessage.SEVERITY_INFO, "Info!", "Cadastrado com sucesso!"));
				
				item.setNome_item("Selecione o item");
				item.setCod_icone("0000000");
				item.setServidor("Arcan");
				item.setRefinacao(null);
				item.setPreco(null);
				item.setDescricao(null);
			} else {
				FacesContext.getCurrentInstance().addMessage(null,
						new FacesMessage(FacesMessage.SEVERITY_ERROR, "Erro!", "Ocorreu um erro!!"));
			}
			con.closeConnection();
		}
	}

	public void deletarItem() throws SQLException {
		ConnectItem con = new ConnectItem();
		if (con.deletItem(item)) {
			FacesContext.getCurrentInstance().addMessage(null,
					new FacesMessage(FacesMessage.SEVERITY_INFO, "Venda Cancelada!", item.getNome_item() + " "));
			item.setNome_item("Selecione o item");
			item.setCod_icone("0000000");
			item.setServidor("Arcan");
			item.setRefinacao(null);
			item.setPreco(null);
			item.setDescricao(null);
		} else {
			FacesContext.getCurrentInstance().addMessage(null,
					new FacesMessage(FacesMessage.SEVERITY_ERROR, "Erro!", " "));
		}
		con.closeConnection();
	}
}