Cannot turn off extension hardening in Excel 2010

Hi,

I can't get this to work. It works fine for Excel 2007 but not Excel 2010. I have tried the two usual methods, setting:

[HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Excel\Security]

"ExtensionHardening"=dword:00000000

and also via Group Policy. The GPO has taken effect and the registry value appears under the Policies key.

However, Excel 2010 refuses to open, for example, an xlsx extension if the format is xls. I get the usual "Excel cannot open the file 'filename' because the format or file extension is not valid. Verify that the file has not been corrupted and that the file extension matches the format of the file.".

The "ExtensionHardening=0" value should disable this and allow Excel 2010 to open such files but it is not working.

Does anyone have any suggestions?

Cheers,

Rob

Continue reading...