I have built a customer portal using Force.com sites. All of the UI is custom built using VF pages with apex controllers. I am displaying some records using pagination with the standard set controller. I basically run a SOQL query, store the results in a list and bind that to a Apex:DataTable and display that data to the user.
Everything is fine except for when I leave a page showing the data for a while and then refresh it, it causes a visualforce error. The debug logs have been of no help. Its as if some kind of timeout or the data has "expired". Has anyone of you come across this error. How can I overcome this or resolve it gracefully instead of having the page crashing.
This is the way I am populating my list from the SOQL query results:
invoiceDetails = [SELECT idtl.Product__c, idtl.Quantity__c, idtl.Unit_Price__c, idtl.tax__c, idtl.Amount__c FROM Invoice_Detail__c idtl where idtl.Invoice__c=:invID ORDER BY idtl.Product__c];