“The file is corrupted and cannot be opened”

Excel or Word stops with “The file is corrupt and cannot be opened.” It sounds final, but this exact message often appears for files that are perfectly fine, so check that first.

Two very different causes

1. Protected View couldn't open it (the file is fine)

Files from email, the internet, Teams or a shared drive open in Protected View, a locked-down mode for files Office doesn't trust. When Protected View itself fails, Office reports the file as corrupt. Signs this is you: the file came from someone else, it opens on their computer, and lots of files from the same place fail the same way, often straight after an Office update.

2. The file really is damaged

The save was cut short by a crash or a pulled USB stick, a sync or download stopped part-way, or a failing drive wrote zeros over part of it. Signs: only this one file fails, it fails everywhere (another computer, Office on the web, LibreOffice), or it's much smaller than it should be.

Free fixes for a Protected View problem

Unblock the file. Save it to your computer, right-click → Properties, tick Unblock at the bottom of the General tab, click OK, and open it again.
Save, then open. Don't open attachments straight from Outlook. Save them to Documents first, then open them from Excel or Word with File → Open.
Update Office. File → Account → Update Options → Update Now. Several bad updates caused this error and were fixed in later ones.
Last resort, for files you trust: File → Options → Trust Center → Trust Center Settings → Protected View and untick the boxes, open the file, save a copy, then tick them again. Leaving Protected View off makes harmful documents more dangerous.

Free fixes for a damaged file

Work on a copy.
File → Open → Browse, select the file, click the arrow next to Open and choose Open and Repair. In Excel, if Repair fails, run it again and choose Extract Data to get the values out.
Look for an earlier version: right-click → Properties → Previous Versions, or OneDrive / SharePoint version history.
Try LibreOffice (free). It reads some damaged files that Office refuses.

Where Office File Repair helps

For a file that's really damaged, Office File Repair takes the .docx, .xlsx or .pptx apart in your browser and keeps everything it can read: text up to the last complete paragraph, spreadsheet rows up to the last complete row, and slides that survived. It can often recover text after a damaged stretch too, and it builds a fresh file that opens normally. The preview is free, and nothing is uploaded.

If the file opens on another computer, don't pay for repair: it's the Protected View problem above.

When nothing can help

A 0 KB file, or one that's all zeros, has nothing in it to recover (see file shows 0 KB). It's also not something this tool fixes if it's an old .doc or .xls, or a password-protected file.

Common questions

Why does Excel say the file is corrupted when it opens fine on another computer?

Usually Protected View failed, not the file. Unblock the file in its Properties, save attachments before opening them, and update Office. If that doesn't work, temporarily turn off Protected View for a trusted file, then turn it back on.

Is it safe to turn off Protected View?

Only briefly, and only for files you trust. Protected View stops harmful documents from running code. Open the file, save a copy, then turn Protected View back on.

What is Extract Data in Excel?

It's the second option in Excel's Open and Repair. When Repair fails, Extract Data pulls out the cell values and, if you choose, the formulas, without the formatting.

How can I tell if the file is really damaged?

Try it on another computer, in Office on the web or in LibreOffice. If it fails everywhere, or the file is much smaller than it should be, it's damaged.

Check your file: the preview is free