Sign up free

Repair a Damaged PDF

Rebuild a PDF that won't open or shows errors, and save a clean copy that works again.

About Repair PDF

Repair PDF files that stopped opening after an interrupted download, a crashed email client or a flaky USB stick, or that make your reader complain about a damaged file. Often the pages are still in there, and what's broken is the index that tells a reader where to find them. The tool reads the file leniently, rebuilds that structure and writes a fresh PDF.

If the first method fails, a second PDF engine tries to open and save it another way. Content that's truly missing, such as the second half of a download that was cut off, can't be brought back. When neither engine can read the file at all, you'll get a clear message instead of a broken download.

How to use Repair PDF

  1. 1
    Upload the damaged file

    Click Choose file or drop the PDF that won't open.

  2. 2
    Start the repair

    Click Repair PDF. There are no settings to choose.

  3. 3
    Download and check

    Save the rebuilt copy and open it to confirm the pages are there.

Why use Cubfile for this

  • Lenient reading

    Broken cross-references, wrong offsets and minor syntax errors are worked around rather than rejected.

  • Second engine as backup

    If one method can't cope, a different PDF engine gets a try.

  • Clean, standard output

    The repaired file is written from scratch, so readers that choked on the original can open it.

  • Honest result

    A file that can't be saved is reported as too damaged, not handed back half broken.

FAQ

Repair PDF: questions and answers

What kind of damage can Repair PDF fix?
Mostly structural problems, such as a broken index, wrong offsets or small syntax errors from a bad save or transfer. Those make readers refuse a file even though its pages are intact. A file that asks for a password isn't damaged; if you know it, Unlock PDF takes the password off.
Can I repair PDF files that were only partly downloaded?
Sometimes. Pages that made it into the file can often be rescued, but anything that never arrived can't be recreated, so downloading it again is usually the better fix.
Will repairing change my content?
No. The pages that can be read are kept as they are; only the file structure around them is rewritten. You can check the repaired copy straight away in PDF Reader.
Does a failed repair use up a task?
No. A task that fails is given back, so a file too damaged to fix doesn't cost you one of your 2 free tries. Free files can be up to 50 MB, VIP files up to 1 GB.
Is my damaged file handled privately?
Yes. It's uploaded over HTTPS, repaired in an isolated process and deleted with the repaired copy after one hour. We don't look inside it.
Share Repair PDF with a friendIt runs in any browser, and they can try it without signing up.

Related tools

PDF Compress PDFMake PDFs smaller for email and upload portals, text stays sharp.
PDF Edit PDFAdd and change text, images, shapes and links right on the page.
PDF Merge PDFCombine PDFs into one file in the order you want.
PDF PDF ReaderRead, search and copy from PDFs in the browser. Nothing is uploaded.
PDF Sign PDFDraw, type or upload your signature and place it on the page.
PDF Split PDFSplit by page ranges, every N pages, or into single pages.
PDF Unlock PDFRemove the password from a PDF you can already open.
PDF Annotate PDFHighlight, underline, comment and draw on PDFs in the browser.