Q: ActionPoller and pageMessages rerender issue I have a pretty batch that is trigger from a VF page. Then I check the batch status using an ActionPoller until it is completed and finally I rerender the batch results. 
Everything is working fine but the pageMessages rerender. I can't figure out why. 
I could check that the msgPanel is rerendering ok using the NOW. But the ApexPage.Messages is empty.
My VF looks like this: 
<apex:outputPanel id="msgPanel">
      <h1>{!NOW()}</h1> 
      <apex:pageMessages id="msg"/>
 </apex:outputPanel>

 <apex:actionPoller interval="5" action="{!checkBatchStatus}" enabled="{!batchStatus}" onsubmit="console.log('checking..');" oncomplete="{!batchComplete}&&refreshJS();" />

<apex:actionFunction action="{!refreshGenerate}" name="refreshJS" reRender="msgPanel,resultsPanel" /> 

In the controller I have this:
public PageReference checkBatchStatus(){

            AsyncApexJob job    =   [select........1];
        if(job.Status == 'Completed'){

            ApexPages.addMessage(new ApexPages.Message(ApexPages.severity.CONFIRM ,
             currentBatch+' Completed. '));
            //some internal checks
            if(errors){
                    ApexPages.addMessage(new ApexPages.Message(ApexPages.severity.ERROR ,errorDescription);
            }

            batchComplete = true;
            batchStatus = false;
        }else{


         batchStatus = true;
             }
  return null;
    }
   public void refreshGenerate(){ 
      // empty method, it is just used by javascript to trigger some rerenders.
    }

Is this a rerender bug of salesforce ?
Please help

A: It seems that the pageMessages behave a bit like a transient variable. Since you rerender the pageMessages element in another request (the actionFunction, rather than the actionPoller), the values are resetted. I haven't confirmed this yet.
If you move the rerender of the pageMessages element as a part of the actionPoller it will work.
