How to Fix a Corrupted PDF File (and When You Can't)

"The file is damaged and could not be repaired." If you're seeing that, or a PDF that opens to blank pages, the file may be corrupted. Often it can be fixed. Sometimes it can't. Here's how to tell the difference and what to try.

First, make sure it's really corrupted

Plenty of PDFs that "won't open" aren't corrupted at all. Rule these out first:

• The download didn't finish. A file that's much smaller than expected (say 40 KB for a 30-page scan) was probably cut off. Download it again.
• It's password-protected and your app isn't asking for the password properly. Try opening it in a web browser, which always prompts.
• It isn't a PDF. Some files are named .pdf but are really a Word document, an image or a web page. Opening it in a text editor shows the truth: a real PDF starts with %PDF.

Why won't my PDF open? covers these in more detail.

What actually corrupts a PDF

• An interrupted download, upload or email attachment
• A USB drive or memory card removed while the file was being written
• An app that crashed while saving
• A sync tool (cloud folder, backup software) that copied the file while it was still being written
• A failing disk

In most of these cases the content (text and images) is still there, but the file's internal index, which tells a PDF reader where each page is, is broken or missing. That's the kind of damage that can be repaired.

How to repair a corrupted PDF

1. Open Repair PDF.
2. Drop in the damaged file.
3. Click repair and download the result.

The tool tries two things, in order:

1. Rebuild the structure. It reads whatever objects it can find, ignores the broken ones, and writes a clean new file. When this works, everything is kept, including selectable text, and the page tells you so.
2. Rebuild from the rendered pages. If the structure is too damaged, it renders each page it can still display as an image and builds a fresh PDF from those. You get a readable document, but the text is no longer selectable. If you need the text, run the result through OCR afterwards.

The file is repaired in your browser, so a damaged contract or bank statement isn't uploaded to anyone.

When a PDF can't be repaired

Repair works when the content is there but the structure is broken. It can't bring back data that's missing:

• Truncated files. If only the first half of the file downloaded, the pages in the missing half are gone. You might recover the first few pages.
• Overwritten files. If the file is all zeros or random bytes, there's nothing to recover.
• Not a PDF at all. No PDF repair tool can help with a file that was never a PDF.

In these cases the fix is to get a fresh copy: download it again, ask the sender to resend it, or check your cloud storage's version history and email "Sent" folders for an older copy.

How to avoid corrupted PDFs

• Wait for downloads and copies to finish before opening or moving the file.
• Eject USB drives properly before unplugging them.
• Don't open a file from a synced folder while it's still syncing.
• Keep a second copy of anything important.

FAQ

Can a corrupted PDF always be fixed? No. Repair works when the file's structure is broken but its content is intact. If the data itself is missing, no tool can recreate it.

Is it safe to repair a PDF online? Most online repair tools upload your file to their server. Repair PDF runs in your browser instead, so the file never leaves your device.

Why does my PDF open on one device but not another? Some PDF readers are stricter than others. A slightly damaged file may open in a browser but fail in another app. Running it through Repair PDF usually produces a file that opens everywhere.

The repaired file has no selectable text. Why? The structure was too damaged to rebuild directly, so the pages were rebuilt as images. Use OCR PDF to make the text searchable again.