I get the following message

View state couldn’t be restored, reload page

on my JSP (with JSF and a4j tags ) , I do not always get this message but it does appear , no exception is written to the log file when this message appears

I have added the session-timeout tag to my web.xml file, its value is set to 35 minutes .

Can anyone please suggest how to get rid of this issue as it is quite annoying on the live code

thank you.