A PDF that refuses to open can be caused by corruption, incomplete download, wrong file type, or viewer incompatibility. Here is how to diagnose and fix each case.
Open the file in Chrome (drag it into the browser window), Adobe Acrobat Reader, and Foxit Reader. Different viewers handle structural damage differently — one may open a file that another cannot.
Right-click the file → Properties (Windows) or Get Info (Mac). Verify the file type is PDF, not an HTML error page or ZIP file that was accidentally saved with a .pdf extension.
Tip: If the file is small (under 10 KB) and won't open, it may be an HTML error page from a failed download. Check by opening it in a text editor — if you see HTML tags, re-download the original file.
Go to pdfeditor.onl/repair-pdf. Upload the file. The tool reconstructs the cross-reference table and attempts to recover all intact content from the damaged file structure.
If the file was downloaded, request a fresh copy. Corruption from incomplete downloads is the most common cause of PDF opening failures.
The file may use features not supported by older Adobe versions. Update Adobe Reader, or continue using Chrome as your PDF viewer.
Yes — completely free at pdfeditor.onl/repair-pdf.