Repair PDF
Repair PDFWhat it's for: fix a PDF that other tools reject as corrupted or malformed.
- Select PDF: open the problem PDF.
- Repair: run the repair pass.
- Save: write the repaired PDF to disk.
Repair uses qpdf, which rebuilds a document's
cross-reference table by scanning the file for the objects it actually
contains, instead of trusting the offsets the file claims. That is what fixes the
commonest kinds of damage: a broken startxref pointer, a missing or truncated
xref table, object offsets that no longer line up, or junk prepended to the file
so it no longer starts where it says it does.
Your pages come back as they were. qpdf preserves the existing page content rather than re-rendering it, so text stays selectable, images are not re-compressed, and page sizes are unchanged.
Repair recovers structure, not content. If parts of the file are simply gone — most often a download or copy that stopped partway, taking whole objects with it — there is nothing left to rebuild them from, and PaperOtter will say so rather than hand you a file that looks repaired and is not.
When that happens, the only real fix is another copy of the document: download or export it again from wherever it came from. A second repair pass will not help, because the missing bytes are not recoverable from what remains.
See also: Compress PDF