Double-click. Nothing. Try again. Spinning wheel, then nothing. Or 'cannot open file'. Or 'damaged'. PDFs refusing to open is annoying but almost always fixable in three minutes. Here's the order to try things in.
Try a different viewer
Many 'broken' PDFs are actually fine — your default viewer just doesn't like them. Drag the file into Chrome, Edge, or Safari. Browsers have lenient PDF rendering that often opens files Adobe rejects. If the browser shows it, the file's fine and your reader is the issue. Update or change reader. Flint also opens many files other tools refuse, so dropping a problem PDF in is a quick test.
Re-download from the source
Half of 'broken' PDFs are truncated downloads. Email gateways sometimes truncate large attachments. Browser downloads can fail silently. Right-click the original link or message, save again, try opening the fresh copy. If the second download is the same size, the file is genuinely as-is. If sizes differ, the first was incomplete.
Check if it's password-protected
Some viewers handle password prompts gracefully; some just hang. If a PDF you've been waiting for refuses to open, ask the sender if there's a password. Banks, lawyers, and government bodies routinely password-protect without flagging it clearly. If your file is unlocked and won't open, none of these apply — it might be genuinely corrupted. Ask the sender to re-share, ideally via cloud link rather than email.
FAQ
What does 'damaged and cannot be repaired' mean?
The file's internal structure is broken — usually a download or sync error. Re-downloading from source fixes most cases. If the original is also damaged, the file genuinely is, and you'll need a fresh copy from the creator.
Could it be malware?
PDFs can carry malicious scripts but most viewers block them by default. The risk is highest with unexpected files from unknown senders. If you weren't expecting the PDF, don't open it; verify the sender first.
Why does my phone open it but my laptop won't?
Different rendering engines, different tolerance for damaged files. Mobile viewers are often more forgiving. The file is the same; the apps differ. Try a different desktop reader.
Most 'won't open' PDFs aren't really broken. Try opening yours in Flint — different engine, often different result.