Common errors

Excel won't open the corrupted file

"Excel cannot open the file because the file format or file extension is not valid"? See why it happens and how to recover the spreadsheet rows.

How the problem shows up

• "The file format or file extension is not valid"
• Excel warns it found a problem with some content
• The workbook opens with missing sheets or rows

Why it happens

Excel .xlsx files are zip packages too. When a file gets cut off (interrupted download, full disk, power loss), parts Excel requires are missing.

What to do now

1. Copy the file before trying anything.
2. Try Open and Repair in Excel.
3. Use Neural Repair's free preview: it recovers the remaining rows and rebuilds the missing parts so Excel accepts the file.

No program fixes 100% of cases. Zeroed files or files encrypted by ransomware have no content to recover, and the diagnosis tells you so before you pay anything.