Question

I have a web page which links to an Excel 2007 worksheet. It is a .xls file and not .xlsx file. When I click on the link I get the usual dialog box to either open/save the Excel file. On clicking ‘Open’, I get the following warning message-

The file you are trying to open,
‘filename.xls’ is in a different
format than specified by the file
extension. Verify that the file is not
corrupted and is from a trusted source
before opening the file. Do you want
to open the file now?

Can I some how suppress this warning message programmatically (i.e. to hide it or prevent it from showing up?) I’m using ColdFusion for web development.

Answer 1

This problem results from a feature called Extension Hardening, and you can find more information about it here

I’ve run into this problem a lot in my projects, and like Jon said, turning off Extension Hardening is something that will have to be done by each client side user.

Unfortunately, the link above also states that there are no expected changes to this code until at least Office 14.