We found a problem with some content in 'filename.xlsx'. Do you want us to try to recover as much as we can? If you trust the source of this workbook, click Yes.

What's actually wrong

This is the modern wording of Excel's corruption prompt: an .xlsx is really a ZIP of XML parts, and Excel found a part it can't parse — a damaged worksheet, chart, PivotTable, or invalid XML written by whatever program generated the file. Clicking Yes runs Excel's built-in repair, which opens the file by deleting or rewriting the broken parts and then shows a log of what it removed. In most cases the raw cell values survive; what usually gets dropped is a specific broken feature. Files exported by non-Microsoft software (ERP exports, reporting tools, Google Sheets, Python/Java libraries) and files interrupted mid-save are the most common triggers, and a file that fails in Excel 2016 will sometimes open cleanly in the more tolerant Excel 365.

Free fixes — try these first

1. Click Yes and read the repair log. Let Excel recover, then read the dialog listing what was removed. If it only mentions calcChain.xml or 'Calculation properties', nothing meaningful was lost — press Ctrl+Alt+F9 to recalculate, then File → Save As under a new name.
2. Use Open and Repair manually. File → Open → Browse → select the file → click the arrow on the Open button → Open and Repair → choose Repair first; if the result is missing data, repeat and choose Extract Data to pull values and formulas without the broken features.
3. Try a newer/more tolerant Excel. Upload the file to OneDrive and open it in Excel for the web, or open it on a machine with Microsoft 365 — users on Microsoft Q&A report files that fail in Excel 2016 opening perfectly in 365.
4. Open it in LibreOffice Calc (free). Calc ignores many XML errors Excel chokes on. If it opens, File → Save As → .xlsx to get a clean rebuild.
5. If the file came out of another system (ERP, BI export, web app), re-export it — corruption during generation or download is common, and a fresh export is often fine. Compare file sizes to spot a truncated download.

If the free fixes fail

If Excel's repair opens a blank workbook, deletes the sheet you actually need, or the file won't open even after Open and Repair and LibreOffice, the XML is broken earlier than those parsers can cope with. Our analyzer reads the raw ZIP and XML directly, salvages cells past the point where Excel gives up, and shows you an honest percentage of what's recoverable before you commit to anything.