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Hi - I have a corrupted Excel file which I can't repair. Cannot attach the file writes that "The file type you are attempting to upload is not allowed." When I open the file writes that "cannot open the file because the file format or the file extension is invalid. Make sure the file is not corrupted and the file name extension matches the format".It's Excel 2010 . Thanks.

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This thread shows a typical workbook-corruption scenario. reported a file Excel would not open and already tried forcing a different extension without finding readable data. Before any repair attempts, make an exact copy of the damaged file and work only on the copy — that preserves the original if a later method succeeds.

Identify the true file type first. Open the copy in a plain-text editor or hex viewer: ZIP-based OpenXML workbooks (.xlsx/.xlsm) begin with bytes 50 4B ... (ASCII "PK"), while legacy binary .xls (OLE compound) begins with hex D0 CF 11 E0 A1 B1 1A E1. If it is ZIP-based, rename the copy to .zip and open with 7-Zip or Explorer; inspect and extract files under xl/worksheets and xl/sharedStrings to recover raw cell text.

Try built-in and alternate importers. Use Excel’s File > Open > select the file > click the arrow by Open > Open and Repair (choose Repair, then Extract Data if needed). Also try opening the copy in a newer Excel build, LibreOffice/OpenOffice, or Google Sheets — different parsers sometimes salvage content Excel 2010 cannot. Launching Excel in Safe Mode (run "excel /safe") is a low-risk additional step.

Check backups and transient saves. Look for Windows Previous Versions (Right-click > Properties > Previous Versions), cloud version history if stored on OneDrive/Dropbox, and Excel’s Unsaved/AutoRecover locations under AppData if enabled. If all attempts fail the workbook is likely unrecoverable; commercial recovery tools are available but carry cost and risk—use them only on copies and prefer trial versions from reputable vendors. After recovery, put a regular backup/versioning plan in place.

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Member Avatar for JacobBrownn

That file is beyond repair. I changed the extension to .XLS and forced it to open up and there is just gibberish inside of it. Do you have a backup or older version you can go back to? may be it will help to restore at least some of the information. See if the following article would help:

Member Avatar for de_boer

Thanks for the advice. Your link was very useful for me! Thank you!

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