Excel says the file format or extension is not valid

The error may indicate corruption, a wrong extension, encryption or a file that is not actually an Excel OOXML document.

License & pricing See repair capabilities

✓ XLSX / XLSM✓ DOCX / DOCM✓ Local repair✓ Windows 10/11

Document diagnostics

OOXML / ZIP integrityOK

XML structureOK

RelationshipsCHECK

Excel / Word internalsREPAIR

Visible progress and current repair stage.

Why can this happen?

XLSX and DOCX files are OOXML packages containing multiple XML parts and relationships. A damaged range, filter, relationship or XML component can affect the behavior of the complete document.

What does KR Office Repair Pro do?

The application analyzes the package locally, reports detected issues and performs only supported structural repairs.

Important: The same error message may have different causes. The software does not guarantee repair of every file.

Have a corrupted Office file?

Inspect the document structure before rebuilding the file manually.

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