OOPS! The title should have read:
AJAX calls give value is not valid error.
Try making payrollExport conversation scoped eg
@Name("payrollExport") @Scope(ScopeType.CONVERSATION)and then ensuring that you start a conversation via pages.xml <begin-conversation> (or similar)
Thanks for the input. PayrollExport was scoped session.
I did find the problem, however. It was a coding problem. In my "refreshEmployees" method I was changing the list of Clients based on a checkbox (Not displayed in this post - My Bad!).
Because I was not refreshing the client drop-down in my AJAX call, I did not notice the list of clients had changed. Since the selected client now was no longer a member of the list of clients, this exception was thrown on the next AJAX call.