This can be reproduced in Estatio. Make sure to uncomment the InvoiceService#validateCalculateInvoiceForProperty method.
- install the demo fixtures (Administration>install demo fixtures)
- Invoices > calculate invoices for property
- leave the first drop-down (for property) deliberately empty
- Hit OK.
Get no error message, though the Wicket ajax box flashes red indicating somethings wrong.
Now enter a valid property in the drop-down,
... triggers stale page exception.
Alternatively you can also enter a period end date which lies before a period start date.