PowerPoint found a problem with content in .pptx (on a file downloaded from Google Slides) / Cannot open pptx downloaded from Google Slides

What's actually wrong

A deck downloaded from Google Slides (or received from someone who made it there) triggers PowerPoint's repair prompt or refuses to open. Nine times out of ten the file isn't corrupt at all — Windows attaches a 'Mark of the Web' to every downloaded file, and PowerPoint's Protected View reacts to that plus Slides' slightly unusual (but legal) XML by crying corruption. The original is still safe in Google Slides, so this is almost always fully fixable; genuine exporter damage is the rare case.

Free fixes — try these first

1. Right-click the downloaded file > Properties > tick Unblock > Apply, then open it. This one checkbox resolves the majority of 'Google Slides pptx won't open' reports.
2. Re-download the file — an interrupted download truncates the ZIP and looks identical to corruption. Compare file sizes if you can.
3. Open PowerPoint in Safe Mode (Win+R, type powerpnt /safe) and open the file from there — if it works, an add-in was the problem, not the file.
4. Use File > Open > Browse, select the file, click the arrow next to Open and pick Open and Repair, then Save As a new name.
5. Go back to the source in Google Slides, make a copy, delete any embedded videos/audio and unusual embedded objects, and download the copy as .pptx — Slides' exporter occasionally writes media parts PowerPoint chokes on.

If the free fixes fail

If Unblock, a fresh download, and Open and Repair all fail — or you no longer have access to the source deck in Google Slides — the exported package itself is malformed. Our free diagnosis tells you in seconds whether it's actually a mislabeled or blocked file (which we fix for free) or real structural damage, with an honest preview of what's recoverable either way.