How to Repair a Corrupted PDF That Won't Open (Free)

You double-click a PDF and get an error instead of a document. Or it opens, but half the pages are blank. It's usually a bill, a certificate or an admit card you need right now. The good news: in most cases the file isn't lost — its internal structure is broken, and that can be rebuilt. This guide explains why PDFs stop opening, the quick checks worth doing first, and how to repair the file for free without installing anything.

The error messages you might be seeing

They all mean the same thing: the viewer couldn't make sense of the file's structure. They don't tell you why, which is what decides whether it can be fixed.

Why PDFs get corrupted

• The download or copy stopped early. A dropped mobile connection, a WhatsApp or email download that didn't finish, a USB drive pulled out too soon, a cloud folder that hadn't finished syncing.
• The internal page index is damaged. Every PDF carries a table that tells the viewer where each page lives. If that table is wrong, viewers give up even though the pages themselves are fine.
• Extra data before the file starts. Some systems add junk in front of the real PDF. Strict viewers refuse to open it.
• It isn't a PDF at all. A government portal or bank site sends an error or "session expired" page, and the browser saves it with a .pdf name. There's nothing to repair — you need to download it again.

Quick checks before you repair

1. Look at the file size. 0 KB, or a few KB for a multi-page document, means the download failed. Download it again first.
2. Try another viewer. Drag the file into Chrome or Edge. Some files that Adobe rejects open fine in a browser, and vice versa.
3. Check that it's really a PDF. Open the file in Notepad (or any text editor). A real PDF starts with %PDF-. If you see <!DOCTYPE html> or <html>, it's a saved web page — log in to the website again and re-download.

If the file passes these checks and still won't open, repair it.

How to repair a corrupted PDF in 3 steps

1. Open Repair PDF and drop in the file. Any file named .pdf works, even if it turns out not to be one.
2. Read the diagnosis. The tool tells you in plain words what went wrong — a broken page index, a cut-off download, a web page saved as PDF — and how many pages came back.
3. Download the repaired PDF. It's saved as filename_repaired.pdf unless you choose a name.

These steps run inside your browser, so the file isn't uploaded anywhere.

If pages are still missing: the optional server repair

For badly damaged files, the Repair tool offers a stronger repair that runs three more engines (qpdf, MuPDF and Ghostscript) on our server. They can sometimes recover pages the browser can't. It only runs if you tick the consent box and click the button; the file is sent over HTTPS and deleted as soon as the repair finishes.

What can and can't be fixed

After the repair

• Text isn't selectable? If some pages had to be recovered as images, the tool says so. Run them through OCR PDF to make the text searchable again — see how to OCR a scanned PDF.
• Need to edit it? Convert it with PDF to Word.
• Too big to upload or email? Shrink it with Compress PDF.

How to stop it happening again

• Let downloads finish completely before opening or moving the file, especially on mobile data.
• Eject USB drives properly, and wait for cloud folders to finish syncing.
• Keep the original email or link until you've checked the saved file opens.
• If a portal keeps giving you an HTML "PDF", log out, log back in and download again — the session had expired. More on admit cards, bills and password-protected statements in downloaded PDF not opening?

Common questions

Is Repair PDF free?

Yes — no watermark, no sign-up.

Can it remove a PDF password?

No. A protected file keeps its password after repair.

Will I lose my text or images?

Usually not. Most repairs keep the original text and images. If pages had to be recovered as images, the result tells you, and OCR can bring the text back.

Related guides