Repair PDF
Check a damaged PDF and rebuild what can still be read. Your file stays on this device.
Checking the file…
Reading every page on your device. Nothing is uploaded.
The file’s list of pages was lost. pdfMB put the pages it found back in order, but it can’t tell whether any are missing, so check the result.
| Now | |
|---|---|
| Pages | |
| Words | |
| Bookmarks | |
| Links | |
| Form fields |
What you can try
- Ask the person who sent it to send it again.
- Download it again. A download that stopped early is one of the most common causes of a damaged PDF.
- Look for another copy in your email, chat history or cloud storage.
- If you made the file yourself, save or export it again from the app that created it.
The repaired file may not be identical to the original. Keep your original file.
Rebuilding the file…
Working on your device. Nothing is uploaded.
0%
The file’s list of pages was lost. pdfMB put the pages it found back in order, but it can’t tell whether any are missing, so check the result.
| Before | After | |
|---|---|---|
| Pages | ||
| Words | ||
| Bookmarks | ||
| Links | ||
| Form fields |
What you can try
- Ask the person who sent it to send it again.
- Download it again. A download that stopped early is one of the most common causes of a damaged PDF.
- Look for another copy in your email, chat history or cloud storage.
- If you made the file yourself, save or export it again from the app that created it.
- No uploadYour file stays on this device.
- Your original stays as it isYou download a new copy. Your file is never changed.
- Free, no sign-upNo account and no daily limit.
What happens to your file
Everything below happens inside your browser, on your own device. The PDF is never uploaded, so nobody else, including us, can see it.
- pdfMB first checks the file. It looks at the file’s index (the table that tells apps where each part of the file is), the list of pages, and the data behind every page.
- It also opens the file with pdf.js, the PDF viewer built into Firefox, and counts what can actually be read: pages, words, bookmarks, links and form fields.
- If the file is fine, you are told so and nothing is changed.
- To repair, pdfMB reads every part of the file that is still intact and writes a new, clean PDF from them, with a new index and page list. Nothing is re-compressed.
- The new file is opened again and counted the same way. If it has fewer pages or less text than pdf.js could read from the damaged file, pdfMB does not offer it.
- A file with only blank pages is never offered as “repaired”.
- Choose the damaged PDF
- Read what was found
- Press “Repair PDF”
- Download and check it
How to repair a PDF
- Choose the damaged PDF. pdfMB checks it and tells you in plain words what it found.
- If the file needs repair, look at the numbers: how many pages, words and bookmarks can still be read.
- Press “Repair PDF”. Keep your original file, because the repaired one may not be identical.
- Download the repaired file and open it to check that the pages look right.
Why PDFs get damaged
Downloads that stopped early
A weak connection or a closed browser can leave a file with its end missing. The end of a PDF holds the index that apps use to find each page, so the whole file can refuse to open.
Email and chat attachments
Some mail systems and chat apps cut large attachments or change their contents on the way. The file arrives with the right name but the wrong data.
Copying to USB drives and memory cards
Pulling out a drive before copying has finished can leave a file only partly written.
Apps that save PDFs badly
Some apps write an index that points to the wrong places. Many readers fix this quietly, but stricter ones show an error or refuse to open the file.
Damaged storage
A failing hard drive or memory card can change a few bytes inside a file. If the damage hits the data of a page, that part of the page is lost.
What it can’t do
- It cannot bring back data that is no longer in the file. If part of a page is damaged, that part stays damaged.
- When a file’s list of pages is lost, pdfMB puts the pages it finds back in order as well as it can. Check the order, and use Organize PDF to fix it.
- Password-protected PDFs must be unlocked first.
- Only the parts of a file that PDF readers use are rebuilt. Damaged fonts or images are copied as they are.
- The repaired file is a new file, so a digital signature in it is no longer valid.
Questions about repairing PDFs
How do I know whether my PDF is really damaged?
Choose it here. pdfMB checks the file’s index and the data of every page, and tells you whether it opens normally, is damaged but fully readable, or is missing pages.
Can every damaged PDF be repaired?
No. If the file’s index or page list is broken, pdfMB can usually rebuild it in full. If the data of a page itself is damaged or missing, nobody can bring it back, and pdfMB tells you which pages are affected.
Why does pdfMB say no repair is needed when my app shows an error?
The file itself is fine, so the problem is probably the app. Try another PDF reader, update the app, or open the file in your browser.
Will the repaired file look the same?
Pages that could be read in full look the same, because their content is copied as it is. The file’s inner layout is new, so the file size may change.
Is my file uploaded?
No. Checking and repairing both happen in your browser.