Recover What You Can From a Damaged PDF
A file that will not open is sometimes truncated, sometimes encrypted, sometimes not a PDF at all. How to tell, and what is recoverable.
Written against the Aug 8, 2026 release·what has changed since
A file will not open. Before trying to repair anything, it is worth finding out which of four quite different situations you are in, because three of them are not damage at all.
Tell them apart first
- 1
Is it a PDF?
A real PDF begins with the characters %PDF. A file saved with the wrong extension, or an HTML error page downloaded under a PDF name, will not open and is not damaged. Opening it in a plain text editor and looking at the first line answers this in seconds.
- 2
Is it encrypted?
A document that asks for a password, or reports that it cannot be opened, may simply be protected. That is not damage and it is not recoverable without the password.
- 3
Is it complete?
An interrupted download is the most common real cause. The tell is a file whose size is suspiciously round, or noticeably smaller than the original. Downloading it again fixes it and nothing else will.
- 4
Is it partly readable?
If some pages open and others do not, the index is damaged rather than the content. This is the case where something can be salvaged.
Salvage, in order of what it costs
- Open it and export. If a viewer can render the pages, exporting from that viewer writes a fresh file with a correct index. This recovers the most and costs the least.
- Extract the pages that work. If only some pages open, pulling those out into their own document saves what is readable rather than losing everything.
- Print to PDF. The last resort, and a real one. It produces a picture of each page, so selectable text and form fields are gone, but a readable document beats an unopenable one.
Whatever you recover, keep the broken original. It is the only copy of anything the recovery dropped, and a second attempt with better information is impossible once it is gone.
- Check the first line, the password prompt and the file size before assuming damage.
- An interrupted download is the most common real cause and re-downloading is the only fix.
- Partly readable means the index is damaged; extract what opens.
- Nothing here rebuilds a broken PDF, and a tool that pretended to would be worse.
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Reviewed and maintained by
Novus Stream Solutions Editorial Team
The Novus Stream Solutions Editorial Team maintains Novus PDF Studio's product documentation, tutorials and PDF explainers. The team checks product claims against the current browser-local implementation and tests, prefers primary specifications and vendor documentation, and corrects material errors openly. The byline identifies the responsible organization; it does not imply a named expert or professional adviser.
Privacy note: every tool mentioned in this article runs entirely in your browser. Nothing is uploaded or queued on a server. A PDF stays in the tab unless you explicitly use Save on this device, which stores that session in this browser without storing passwords. More on the how it works page.