When an Excel workbook will not open
Modern XLSX files are ZIP packages containing workbook XML, worksheets, shared strings, styles and relationships. An interrupted save, damaged transfer or broken ZIP directory can make Excel reject the whole workbook even when useful worksheet data still survives.
What MakeFileWork verifies
After recovering the container, MakeFileWork checks the required OOXML package parts, confirms the Excel workbook main part, inspects worksheet references and validates that referenced worksheet parts still exist. If a worksheet is already proven missing, it can conservatively remove only that dead manifest reference rather than pretending the lost sheet was recovered.
See recovery evidence before download
For repaired XLSX files, MakeFileWork can show worksheet names and a bounded sample of recovered cell values locally before download. This helps distinguish a structurally repaired workbook with surviving data from an empty or incomplete recovery. Missing formulas, cells, charts or media are never fabricated.
Common Excel errors this workflow is designed for
This repair path is relevant when Excel reports “Excel found unreadable content”, “The file format or file extension is not valid”, “Excel cannot open the file” or a workbook corruption warning. You can also paste that rejection message into the assistant: the same repair-intent classifier routes the file into diagnosis and conservative recovery rather than a generic conversion.
Know what survived before trusting the result
A repaired download is not treated as proof by itself. MakeFileWork distinguishes verified or partial recovery from an incomplete Office package, and shows bounded recovery evidence before download when readable workbook content survives. Incomplete structural recovery is not presented as a successful repair.
Privacy
The current XLSX diagnosis, ZIP reconstruction, structural validation and preview run locally in your browser. Your spreadsheet is not uploaded for this repair flow.