I have a page with a button and when the button is pressed, the window location is assigned to a URL where the backend Java process writes out an Excel file to the HTTP response stream so that the user can download the file. I use window.location.assign as I believe it cannot be done asynchronously with Ext.Ajax.

Now when an exception occurs on the server side while generating an Excel file, the server returns an Internal Server Error 500. My question is, is there any way to capture this error on the client side and show a user-friendly error message with Ext.MessageBox and the message returned with the Java exception?