Erro Target Unreachable, 'null'

javax.el.PropertyNotFoundException: /pages/guiaconsulta.xhtml @545,118 value="#{cadguiaMbean.obj.obs}": Target Unreachable, ‘null’ returned null

at com.sun.faces.facelets.el.TagValueExpression.getType(TagValueExpression.java:100)

at org.primefaces.renderkit.InputRenderer.findImplicitConverter(InputRenderer.java:170)

at org.primefaces.renderkit.InputRenderer.findConverter(InputRenderer.java:190)

at org.primefaces.renderkit.InputRenderer.getConvertedValue(InputRenderer.java:196)

at javax.faces.component.UIInput.getConvertedValue(UIInput.java:1030)

at javax.faces.component.UIInput.validate(UIInput.java:960)

at javax.faces.component.UIInput.executeValidate(UIInput.java:1233)

at javax.faces.component.UIInput.processValidators(UIInput.java:698)

at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1214)

at org.primefaces.component.dialog.Dialog.processValidators(Dialog.java:359)

at javax.faces.component.UIForm.processValidators(UIForm.java:253)

at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1214)

at org.primefaces.component.panel.Panel.processValidators(Panel.java:293)

at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1214)

at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1214)

at javax.faces.component.UIViewRoot.processValidators(UIViewRoot.java:1172)

at com.sun.faces.lifecycle.ProcessValidationsPhase.execute(ProcessValidationsPhase.java:76)

at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)

at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)

at javax.faces.webapp.FacesServlet.service(FacesServlet.java:593)

at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1550)

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)

at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)

at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161)

at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:331)

at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)

at com.sun.enterprise.v3.services.impl.ContainerMapper$AdapterCallable.call(ContainerMapper.java:317)

at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:195)

at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:860)

at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:757)

at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1056)

at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:229)

at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)

at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)

at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)

at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)

at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)

at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)

at com.sun.grizzly.ContextTask.run(ContextTask.java:71)

at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)

at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)

<p:commandButton  value="Observação" onclick="obs.show();"  style="height: 25px; font-size: 10px" />                            


            <p:dialog id="modalobs" header="#{msg.guiaconsultaspsadtsol_preencherobs}" widgetVar="obs" modal="false" height="100" width="600" >  
                <p:inputTextarea value="#{cadguiaMbean.obj.obs}" maxlength="300" style="height: 60px;width: 570px;"/>
                
                <p:commandButton  value="Ok"  onclick="obs.hide();" style="height: 35px; font-size: 12px" />                            
                
            </p:dialog>   



@ManagedBean(name="cadguiaMbean")
@ViewScoped
public class CadguiaMb extends ManagedBeanGenerico<Cadguia, CadguiaServico> implements Serializable {

    private Cadguia obj = new Cadguia();
    
    @Override
    public void salvar(ActionEvent ev) throws Exception {
        try {     
        
        .........
        ****depois que salva da erro
        
        }
        
 }