Why Are My PDFs Not Merging?

Merge PDF works by copying the pages from each of your files directly into a new document, so a merge will fail if one of the source files can't be opened at all — most commonly because it's corrupted or protected with a password. If you see an error, try merging your files one pair at a time to find which one is causing the problem, then re-save or remove the password from that file before trying again. If every file opens normally on its own, try refreshing the page and re-uploading them.