Guides
"We Found a Problem with Some Content": How to Repair a Corrupted Excel File
Updated 2026-10-13
When Excel says a workbook is corrupt, your data is usually still there. An .xlsx file is a ZIP package of XML parts, and typically only one or two parts are damaged. Work through the steps below from least to most invasive.
The error messages
Depending on your version, you will see one of these:
- "We found a problem with some content in 'file.xlsx'. Do you want us to try to recover as much as we can? If you trust the source of this workbook, click Yes."
- Older versions: "Excel found unreadable content in 'file.xlsx'. Do you want to recover the contents of this workbook?"
- "Excel cannot open the file 'file.xlsx' because the file format or file extension is not valid."
- After a recovery: "Excel was able to open the file by repairing or removing the unreadable content", followed by a repair log.
Why files get corrupted
- Saving was interrupted: a power cut, an Excel crash, or a USB drive removed too early.
- A download, email attachment or cloud sync was incomplete, so the file is truncated.
- Another program exported a workbook with a structure Excel doesn't accept.
- The file was edited directly on a network share or USB drive and the connection dropped.
Step 1: Back up the file
Copy the damaged file to your local disk and work only on the copy. Keep the original untouched so you can start again if a step makes things worse.
Step 2: Let Excel recover it
When Excel asks whether to recover the workbook, click Yes. Read the repair log Excel shows afterwards; it lists what was repaired or removed, such as conditional formatting or a drawing on a sheet. If the data looks complete, use Save As to save a new file instead of overwriting the original.
Step 3: Use Open and Repair
If the file won't open at all:
- In Excel, choose File > Open > Browse and select the damaged file.
- Click the arrow next to the Open button and choose Open and Repair.
- Click Repair first, which tries to keep data and formatting.
- If that fails, repeat and choose Extract Data. It recovers cell values; formulas may be lost, but the data is saved.
Step 4: Look for an earlier version
- For files on OneDrive or SharePoint, restore a version from before the damage in Version History.
- If Windows File History is on, right-click the file and open Properties > Previous Versions.
- If Excel crashed before you saved, try File > Info > Manage Workbook > Recover Unsaved Workbooks.
"File format or extension is not valid": check what the file really is
Open the file in Notepad and look at the first characters:
- It starts with
PK: it really is an .xlsx (ZIP) file with a broken structure. Use the online repair below.
- It starts with
<html or lines of comma-separated text: it is a web page or a CSV that was renamed to .xlsx. Convert it with the converter.
- It starts with unreadable symbols: it may be an old .xls file. Use the converter as well.
Step 5: When Excel can't fix it, try xlszip
Excel's repair often drops a damaged part entirely, and a whole sheet disappears with it. xlszip Repair works differently:
- rebuilds the package the way Excel reads it and trims broken fragments inside each part, keeping every row it can;
- recovers sheets that exist in the package but were never registered;
- recovers parts one by one even when the ZIP directory is missing, and keeps every complete row before the break in a truncated sheet;
- copies undamaged parts byte for byte and re-verifies the repaired ones.
Upload the original damaged file, not a copy Excel already repaired and saved, which may have lost content. Password-encrypted files and files that were completely overwritten can't be repaired.
How to prevent it
- Turn on AutoSave, or shorten the AutoRecover interval.
- Copy files to your local disk before editing instead of working on USB drives or network shares.
- Wait until a large file has finished saving before closing Excel or removing the drive.