I get the following error adding Excel files:“The file you are trying to open is in a different format than specified” when adding excel files"

I get the following error adding Excel files:

“The file you are trying to open is in a different format than specified” when adding excel files"

1. Launch the Windows Registry Editor (Windows Start button -> Run... -> type: regedit)
2. Navigate to the "HKEY_CURRENT_USER\Software\Microsoft\Office\OfficeVersionNumber\Excel\Security" key, where "OfficeVersionNumber" has to be matched with the version number of your installed MS Office.

[OfficeVersionNumber]

Office 2003 -> 11.0
Office 2007 -> 12.0
Office 2010 -> 14.0
Office 2013 -> 15.0
3. Insert a new DWORD(32 bit) value:

- Value name: ExtensionHardening
- Value type: REG_DWORD
- Value data: 0 (default value is 0)

You might need to restart the computer for these changes to take effect.