A delivery for a BI 4.x WebI document was created in the legacy Flash user interface. The delivery format is "Excel". The following error occurs when attempting to open that delivery in the HTML5 user interface:
Excel (.xls) for BI 4.x Webi is not supported in this UI. Would you like to delete it?
The Excel format section of the legacy Flash user interface was created before BusinessObjects supported the .xlsx format for WebI. BI 4.x does not support .xls for WebI. If the user selected "Excel" (which is .xls) in a delivery or Delivery Template, then InfoBurst automatically requests .xlsx from BI 4.x because that is the only Excel format BusinessObjects supports. The HTML5 UI now offers .xls and .xlsx separate formats where applicable. Therefore, the selection of "Excel" for BI 4.x WebI in the legacy Flash user interface is now invalid in the HTML5 user interface.
To resolve the issue, open the affected delivery or Delivery Template in the Flash user interface, change the format to "Excel 2007" and save. The delivery can then be opened in the HTML5 user interface.