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How to Repair a Corrupted PDF Online
When a PDF will not open, the file is sometimes recoverable and sometimes not. This walkthrough shows how to try the Repair PDF tool, what each result means, and how to check that the repaired file is what you expected.
Ready to try the tool this guide describes?
Before you start
- Keep the original file. Repair PDF never changes it, but keep your own copy anyway.
- Make sure the file is not password-protected. Encrypted files are rejected, and a password prompt is not the same as damage.
- Check that the file is under 25 MB and still begins with a PDF header (open it in a text editor: the first characters should read %PDF-).
Repairing the file
- Open Repair PDF and choose the damaged file, or drag it in.
- Select Attempt to repair. The file is uploaded to a private temporary folder for the attempt and deleted immediately afterward.
- Wait up to a minute for large files. The tool first tries a standard structural rebuild.
- If the download starts, open the repaired file and read the summary shown on the page.
Reading the result
The summary tells you how many pages the repaired file contains. It does not claim how many the original had, because a damaged file often cannot say. Compare the count with what you expected, then page through the document.
If the tool says a heavier rebuild was needed, the document was re-interpreted rather than just re-indexed. Fonts, form fields, links or bookmarks may differ from the original, so check anything that matters.
If the tool says no structural damage was detected, the file was already readable to the repair engine. The download is a clean rewrite, and the problem you saw may be in the viewer that failed to open it.
When it cannot be repaired
Some files cannot be recovered, particularly ones cut off before most of their content was written. In that case no download is offered. Get the file again from its source, look for an earlier version, backup or cloud copy, or ask the sender to re-send it, ideally as a compressed archive so the transfer cannot alter it.
How to Repair a Corrupted PDF FAQ
- How long does a repair take?
- Usually seconds; large or complex files can take up to a minute. If the server is busy you may be asked to try again shortly.
- Is my original file modified?
- No. The tool works on a temporary copy and gives you a separate repaired file.
- The repaired PDF opens but a page is blank. Is that a failure?
- Not necessarily. Blank pages are legitimate, and the tool does not reject a page for having little content. Compare against the original source if you expected content there.
- Can it remove a password?
- No. Password-protected PDFs are rejected, and Repair PDF does not bypass any restrictions.
- What file types does it accept?
- PDF files (.pdf) up to 25 MB that still contain a PDF header. It cannot turn a non-PDF file into a PDF.
Related guides
- Why PDFs Get CorruptedHow a PDF is built (header, objects, index, trailer), the usual causes of damage, which kinds of damage a repair can fix, and which — like truncated files — cannot be brought back.
- PDF Won't Open ChecklistA symptom-driven checklist for a PDF that will not open: check the size and first bytes, try another viewer, rule out passwords and bad transfers, and only then try a repair.
