How to repair a damaged or corrupted PDF
A PDF can become corrupted when a download is interrupted, a storage device fails, or a file is incompletely written by a faulty application. The result is a document that refuses to open, shows an error, or displays only part of its pages. Repairing the file attempts to rebuild its internal structure so that as much of the content as possible can be recovered.
This tool reads what remains of the damaged file and reconstructs a valid PDF you can open again.
Before repairing, it is worth ruling out the simple causes: re-download the file if it came from the web or an email — a fresh download fixes a surprising number of "corrupt" PDFs — and try a different viewer, since some readers are stricter than others. If the file fails everywhere, upload it here and let the tool rebuild its structure.
Step by step
- Open the Repair PDF tool and upload the file that will not open correctly.
- Press Process to let the tool analyse and rebuild the document structure.
- Wait while the recoverable pages and resources are reassembled.
- Open the repaired file to check how much content was restored.
- Download the rebuilt PDF.
Limits and formats at a glance
| Input | A damaged or unreadable PDF up to 20 MB free (1 GB with PRO) |
|---|---|
| What is rebuilt | Cross-reference table, object structure, page tree |
| Recovery rate | Depends on the damage — truncated files and broken indexes recover best |
| Original file | Never touched: the repair works on an uploaded copy |
| Output | A new, standards-compliant PDF containing everything that could be recovered |
| Cost | Free, no account required |
Why use this tool
Losing access to an important document — a signed agreement, a tax record, a piece of coursework — is stressful, and re-creating it is not always possible. A repair attempt is the fastest and lowest-risk first step before you give up on a file or hunt for an older backup.
Because the tool works on a copy you upload, your original damaged file stays exactly as it is, so there is no harm in trying.
Corruption usually shows up as one of a few symptoms: the file opens to a blank or grey page, the reader reports a damaged or malformed document, pages are missing, or fonts and images fail to render. These often come from an interrupted download, a full or failing disk, a sync conflict in cloud storage, or an email attachment that was truncated. The repair rebuilds the cross-reference table and object structure the reader relies on, which is frequently enough to bring an "unopenable" file back to life.
Repair is also the right first move when a file misbehaves in subtler ways: printing fails halfway, a page renders as grey boxes, text is garbled in one viewer but fine in another, or another tool rejects the file as malformed. Rebuilding the structure normalises the PDF so that viewers, printers and converters all parse it the same way — many "problem files" that were never visibly broken become cooperative after a pass through Repair.
Is it safe? Your privacy
The file you upload is used only for the repair attempt and is deleted automatically from our servers soon afterwards. We never store or examine the contents of your documents.
Troubleshooting: common problems and fixes
- The repaired file opens but some pages are blank. — The data for those pages was lost in the original damage, not in the repair. Check whether an earlier version survives in cloud-storage version history or an old email attachment.
- The tool says the file is not a PDF at all. — If the file was renamed from another format (for example .docx to .pdf) there is no PDF structure to rebuild. Recover the original format instead, then convert it properly with Office to PDF.
- The file asks for a password instead of opening. — That is encryption, not corruption — the document is intact. Open it with the password, or remove the protection with Unlock PDF.
- The repair succeeded but the file is now larger. — Rebuilding can leave recovered data loosely packed. Run the result through Compress PDF to bring the size back down.
Frequently asked questions
Can every corrupted PDF be recovered?
Not always. If the underlying data is severely damaged some content may be unrecoverable, but many files that simply will not open can be restored.
Will repairing change my document?
It only rebuilds the file structure. Recoverable pages keep their original text and images.
What causes a PDF to become corrupted?
Most often an interrupted download or transfer, a full or failing storage device, a cloud-sync conflict, or an application that crashed while saving. The bytes get truncated or scrambled, so the reader can no longer parse the file.
My PDF asks for a password — is that corruption?
No. A password prompt means the file is encrypted, not damaged. Use the Unlock PDF tool with the correct password instead of Repair.
Should I try repair before restoring a backup?
Yes — it takes seconds and works on a copy, so your damaged original is never altered. If the repair falls short, you can still fall back to a backup.
Will I lose quality on the recovered pages?
No. Repair reconstructs the file structure and copies the existing page content as-is; it does not re-compress or rasterise anything that survives.
Why does the file open on my phone but not on my computer?
Viewers differ in how forgiving they are: some tolerate structural errors that others reject. Repairing normalises the file so it opens consistently everywhere.
Can Repair recover a file that was overwritten or deleted?
No. It rebuilds damaged data that still exists inside the file; it cannot restore content that was never saved or has been overwritten. For that, check backups or your cloud provider’s version history.