Hi Sergery_Skalyga,
I'm not sure I'm following you precisely. You're using the WebExcelExporter. You click some button to go to the server to export the data to excel. And while this is happening, they click another button and get some sort of exception? Could you maybe attach a sample to demonstrate what's going on? Or maybe a picture of the exception to determine if it is a problem in our code or your application.
regards,
David Young