[Solved] Excel Cannot Open the File Because the Extension Is Not Valid
https://www.stellarinfo.com/article/excel-cannot-open-the-file-because-the-extension-is-not-valid.php
WEBFeb 5, 2024 · Workaround 1 – Change the Default File Format. By default, an Excel file is saved in .xlsx or .xls file format. Trying to open the file with a different or incorrect extension may cause the 'Excel cannot open the file because the extension is not valid' error. To fix the error, try changing the Excel default file format by following these steps:
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