How to fix “File is not in a recognizable format” error when opening EXCEL(x) 2007 -2010 files.

In a Windows 7 based computer with Office 2003 (Pro) and the 'Microsoft Office Compatibility Pack for newer versions of  Word, Excel, and PowerPoint File formats' already installed, the following error appeared when the user tried to open Excel workbooks that were created in newer Office 2007 or 2010 versions (*.xlsx) : “The (excel) file is not in a recognizable format…..". Uninstalling and re-installing MS Office compatibility pack didn’t resolve this issue. Finally, after doing some research, the following solution fixed Excel’s “unrecognizable format” error message:

How to fix ‘File is not in a recognizable format’ error message in Excel.

1. Right-click on any “.xlsx” file you want (e.g. ‘Book1.xlsx’) and go to “Open With” > “Choose Default program”.

2. At Open With dialog, click “Browse”.

3. Navigate to "C:\Program Files\Microsoft Office\Office12", to select the “Moc.exe” * file and click “OK”.

* MOC = Microsoft Open XML Converter.

4. Now open your “.xlsx” workbook. Your problem should be gone!

That's it!

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Konstantinos Tsoukalas

Konstantinos is the founder and administrator of Wintips.org. Since 1995 he works and provides IT support as a computer and network expert to individuals and large companies. He is specialized in solving problems related to Windows or other Microsoft products (Windows Server, Office, Microsoft 365, etc.).

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