Repair a damaged PDF
Rebuild a PDF that will not open: a broken index, a cut-off download or a wrong stream length. It says what was wrong and refuses if nothing is left.
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Repair PDF in three steps
A PDF that will not open is usually damaged at its end rather than in its pages. The last part of the file is an index saying where every object begins, and a download cut short, a tool that writes the index wrong, or bytes appended after the end are enough for a reader to give up, even though every page is still there.
How it recovers the file
The file is read by scanning for its objects one after another instead of trusting the damaged index. If the list of pages is gone, it is rebuilt from the pages that survived, in the order they sit in the file. A file cut short is read up to the last object that is complete. Then a new file is written with a fresh index.
A second, independent PDF reader then has to open the repaired file and draw every page. If it cannot, no file is offered, because a repair that only looks like one is worse than none.
It tells you what was wrong
Before anything is rebuilt, the damage is measured on the file as it arrived: a missing end marker, an index pointer past the end of the file, index entries pointing at the wrong place, streams with the wrong length. The result lists what it found and what it did, and counts any page that could not be saved.
The file is repaired by a worker in your browser and is never uploaded, which matters for a document damaged in transit that you still need to keep private.
- 1
Choose the PDF that will not open
- 2
Let the pages be found and the file rebuilt
- 3
Download the repaired copy and read what was wrong
Frequently asked questions
What kinds of damage can it fix?
A broken or missing cross-reference table, a pointer to it that is wrong or past the end of the file, extra data after the end marker, streams that declare the wrong length, a missing trailer or catalog, and a file cut short, as long as whole pages survive before the cut.
What happens to pages that were cut off?
A page whose content did not survive is left out and counted in the result, rather than returned as a blank page that looks like part of the document. Everything before the damage is kept.
When does it refuse?
When there is no PDF header, when no complete page survives, or when the rebuilt file still cannot be opened and drawn by a second PDF reader. In each case it says which, and no file is offered.
Can it open a password-protected PDF?
No. An encrypted file needs its password first. If you know it, remove it with Unlock PDF and then repair the unlocked copy.