Troubleshooting
How to Repair a Corrupted PDF
What "the file is damaged" actually means, which kinds of damage are recoverable, and the steps that get a broken PDF open again.
A PDF that will not open is usually not as broken as the error message suggests. Most damage is to the index rather than the content, and an index can be rebuilt.
Try repairing it
- 1Open the Repair PDF tool and add the file.
- 2Run the repair. The document structure is rebuilt from whatever objects can be located.
- 3Open the result and check the page count against what you expect.
- 4Page through it — partial recovery is common and worth knowing about before you rely on it.
What is actually broken
| Problem | Recoverable? |
|---|---|
| Damaged cross-reference table | Usually yes — this is the common case |
| Missing or malformed trailer | Often, by scanning the file for objects |
| Corrupted individual objects | Partially — those pages may be lost |
| Truncated download | Whatever arrived; the rest is simply not there |
| Wrong file type renamed .pdf | No — it was never a PDF |
| Encrypted with an unknown password | Not damage; you need the password |
The cross-reference table is a map of where every object lives in the file. Damage it and a reader cannot find anything, even though the content is entirely intact — which is why rebuilding the map so often restores the whole document.
Before assuming corruption
- 1Try a different reader — Chrome, Firefox and Preview are all more tolerant than some desktop applications.
- 2Check the file size. A few hundred bytes means the download failed rather than the file being damaged.
- 3Download it again, if it came from the web or an email.
- 4Check it is really a PDF — open it in a text editor and look for %PDF in the first line.
- 5Try it on another device, to rule out one broken installation.
A surprising number of "corrupted" PDFs are simply files a particular reader dislikes.
How PDFs get damaged
- Interrupted downloads and transfers.
- A USB drive removed while writing.
- Failing storage media.
- Software crashing mid-save.
- Cloud sync conflicts producing a half-written file.
- Email systems mangling an attachment in transit.
If repair does not work
Check for other copies before doing anything drastic: your email sent folder, the cloud drive's version history, a backup, the person who sent it. Cloud storage keeps previous versions for weeks and this is exactly what that feature is for. An earlier copy that opens is worth more than any amount of forensic recovery.
Do it now
Repair PDF
Fix corrupted or damaged PDF files. It runs in this browser tab — your file is not uploaded anywhere.
Open Repair PDFFrequently asked questions
Can every corrupted PDF be repaired?+
No. Index damage usually can be. Missing data cannot be recreated.
Why does my PDF open in Chrome but not Acrobat?+
Browsers are more forgiving of malformed structure. It confirms the content is intact, which is good news.
Will repair recover everything?+
Often, but partial recovery happens. Check the page count and read through before relying on it.
Can I recover a PDF that never finished downloading?+
Only the part that arrived. Download it again.