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I am getting the following error warning when opening an .xls file generated using 'CarlosAg.ExcelXmlWriter.dll' in Excel 2007:

The file you are trying to open,'', 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?

Any ideas how I can resolve this?

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Related: –  Mehper C. Palavuzlar Jun 16 '10 at 13:37

4 Answers 4

There's a Microsoft discussion of the issue which provides some mechanisms to resolve:

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It seems that the .xls file (Microsoft Excel 97-2003 format) is actually an .xlsx file (Microsoft Excel 2007 format). Changing the file extension from .xls to .xlsx should clear the warning message.

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In your VBA code, use this command:

Application.DisplayAlerts = False

this will suppress any such warnings.

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It's xml spreadsheet 2003 format, the correct extension is xml which is why it does not need excel installed.

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I think you meant to say .xlsx, not .xml? –  SamB Jan 13 '14 at 5:51

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