How to repair a damaged PDF
- Try downloading it again first
If the original source is still available, a clean download is better than any repair. Repair is for when that is not an option.
- Upload the damaged file
Files that no reader will open at all are the intended case.
- Run the repair
The structure is rebuilt with two different engines, the second attempted only if the first fails.
- Check the page count
The result panel reports how many pages were recovered. If that is fewer than you expected, the missing pages were not in the file.
Why this matters for exam and study documents
A paper downloaded over a patchy connection on the way home is the classic case. The file is there, it is nearly the right size, and nothing will open it. Repair recovers it often enough to be worth the thirty seconds.
What is kept, what changes, and what this will not do
These are the tools that genuinely alter a document rather than rearranging it, so the trade-offs are real and worth reading before you delete the original.
Kept
- Every page object that survived intact
- Text, fonts and images on those pages
Changed
- The internal structure is rewritten
- Damaged annotations, form fields and bookmarks may be dropped
- Metadata may be reset
Limits
- Content that never finished transferring cannot be recovered, by this or any tool.
- Repair is not decryption: an encrypted file still needs its password.
Questions and answers
Can you recover a file that is only half downloaded?
Sometimes. If the first half transferred cleanly, those pages usually come back and the rest do not. The result panel gives you the honest page count.
My PDF opens but shows blank pages. Will this help?
Possibly. Blank pages can mean a damaged content stream, which a rebuild sometimes fixes. They can also mean the pages really are blank, in which case nothing will change.
Is a 'repaired' file safe to rely on for an exam?
Check it page by page against what you expected before you rely on it. A repair restores structure, not certainty.