Optimize & secure guide
Repair a PDF That Won't Open
Updated
Short answer: Drop the file into Repair PDF; it rebuilds the PDF's internal index and, if that isn't enough, rewrites the whole file so the pages open again.
“The file is damaged and could not be repaired”, “Failed to load PDF document”, a viewer that shows nothing: these errors usually mean the file's internal map is broken, not that the pages are gone.
Step by step
Step 1: Try a second viewer, such as a different browser. If it opens there, the file may only need re-saving.
Step 2: Open Repair PDF and drop the damaged file.
Open Repair PDF(runs on our server)Step 3: Download the repaired copy and check every page, especially the last few.
Step 4: If fonts or later conversions still misbehave, convert the repaired copy to PDF/A, which embeds fonts and normalises the file.
Open PDF to PDF/A(runs on our server)Step 5: If the file came from a download or an email attachment, also fetch a fresh copy, in case the original was truncated.
Why this works, and what to watch for
A PDF ends with a cross-reference table, an index that says where every object in the file starts. Readers jump straight to it to find pages. If a program wrote the file badly, if it was edited and saved by something that miscounted, or if a few bytes changed on a USB stick, that index points to the wrong places and strict readers give up, even though the pages themselves are intact.
Repair PDF first rebuilds that index by scanning the file for the objects themselves, then saves a clean copy. That fixes most files and keeps everything: text, fonts, form fields and bookmarks. If the structure is too broken for that, we fall back to rewriting the whole document with Ghostscript, which interprets the pages and writes them out as a new PDF. That recovers the visible content but can drop interactive parts such as form fields and bookmarks.
Some damage can't be undone. A half-finished download or an attachment cut off by a mail server is missing the end of the file, often including pages; nothing can recreate data that isn't there. A quick tell is file size: if the file is far smaller than you'd expect, get a fresh copy. Files that were encrypted and then damaged usually can't be recovered either.
If a repaired file still behaves oddly in other tools, such as missing fonts in a conversion, converting it to PDF/A embeds fonts and normalises the structure, which gives later tools a cleaner starting point.
Repair runs on our servers and counts as one conversion toward your daily limit. The file is processed and returned straight away and isn't stored.