PDFViewerPDF not opening: how to find the cause and fix it
A PDF that will not open is almost always one of five things: the file is not actually a PDF, it needs a password, the download was cut short, it is a scan too large for the device, or the browser is set to download PDFs instead of showing them. Run the quick checks below in order; each takes under a minute and tells you which fix applies.
Quick checks, in order
- Try a second viewer. Drop the file onto pdfviewer.work. If it opens there, the file is fine and the problem is your default app or a browser setting. If it reports "This PDF is password-protected", you have an encrypted file; skip to that section.
- Look at the file size. A PDF of 0 KB or a few hundred bytes is an empty or failed download. Download it again, from the original source if possible.
- Check the header. A real PDF starts with the characters
%PDF. Open the file in a plain text editor (Notepad, TextEdit) and look at the first line, or on a command line runhead -c 8 file.pdf(macOS, Linux) orFormat-Hex file.pdf -Count 8in PowerShell. If you see<htmlinstead, you downloaded a login page or an error page with a .pdf name. - Try another device. A file that opens on a laptop but not on a phone is usually a memory problem with a large scan, not a broken file.
Cause by cause: what is wrong and what fixes it
| Symptom | Likely cause | Fix |
|---|---|---|
| Password prompt, or the viewer's password message | Encrypted PDF (open password) | Enter the password in Acrobat, Preview or Chrome and save an unencrypted copy; see remove a password from a PDF. No viewer can open it otherwise. |
| "Failed to load PDF document", "file is damaged" | Truncated or corrupted download, or not a PDF | Check the header and size; re-download; ask the sender to resend as an attachment rather than a link. |
| Opens as text or garbage | Wrong extension on a non-PDF file | Check the header; rename to the real type (.html, .docx, .zip) or get the proper file. |
| Blank white pages | Fonts failed to render, or the file is a scan still loading | Wait, zoom, try another viewer; print to PDF from a viewer that renders it to make a clean copy. |
| Tab freezes or crashes on a phone | Large scan exhausting memory | Open on a laptop; reduce the file with compress PDF tools before sending to phones. |
| File downloads every time instead of showing | Browser set to download PDFs | Change the setting; details below and in open a PDF in your browser. |
Browser settings that stop PDFs from opening
Chrome has a switch at chrome://settings/content/pdfDocuments with two options: Download PDFs, and Open PDFs in Chrome. If "Download PDFs" is selected, every PDF link saves a file and nothing displays, which looks like a broken file but is not. Edge has the same toggle at edge://settings/content/pdfDocuments, named "Always download PDF files". In Firefox, Settings, General, Applications lists PDF with a dropdown; "Open in Firefox" shows it inline, while "Save File" downloads it.
Corporate policies sometimes lock these settings, and some antivirus products scan PDFs before the browser can show them, leaving a spinner. If you cannot change the setting, download the file and open it at pdfviewer.work instead; the Chrome PDF viewer comparison explains the differences.
Repairing a damaged PDF
If the header is right but the file still fails, the structure inside is broken: a missing end-of-file marker, a bad cross-reference table, or an attachment that was cut off in email. Tools that can rebuild it:
- qpdf:
qpdf --check file.pdfreports what is wrong;qpdf file.pdf fixed.pdfrewrites the structure and recovers many files. - Ghostscript:
gs -o fixed.pdf -sDEVICE=pdfwrite file.pdfre-renders the pages and tolerates a lot of damage. - Adobe Acrobat: opens damaged files more often than other apps and offers to save a repaired copy.
- Regenerate it. If you made the file, export it again from the source document. If someone sent it, ask for it zipped; some mail systems alter attachments.
Background on what the format expects inside a file is on the what is a PDF file page, and the PDF passwords page covers the encrypted case in depth.
Preventing it next time
Most unopenable PDFs come from the transfer, not the file. Send attachments rather than preview links from mail clients, which sometimes export a partial file. Zip a large PDF before uploading it to a portal with a size limit. Keep scans at 200 to 300 dpi; a 600 dpi color scan of a 100-page document is enormous for no benefit and will not open on a phone. And when a web page offers "View PDF", check that the downloaded file ends in .pdf and starts with %PDF before forwarding it to anyone.
Frequently asked questions
Why won't my PDF open?
Most often it is a broken download, a file that is not really a PDF, a password-protected file, a huge scan on a phone, or a browser set to download PDFs. Check the file size and the %PDF header first.
How do I know if a PDF file is corrupted?
Open it in a text editor and look for %PDF on the first line, check that the size is more than a few kilobytes, and run qpdf --check if you have it. If two different viewers fail, the file is damaged.
Why does Chrome download PDFs instead of opening them?
The setting at chrome://settings/content/pdfDocuments is on Download PDFs. Switch it to Open PDFs in Chrome, or open the downloaded file in another viewer.
Why does my PDF open blank?
Fonts or images failed to render, the file is a slow-loading scan, or the download was truncated. Try another viewer, wait for a large file, and re-download if it stays blank.
Can a corrupted PDF be repaired?
Often. qpdf and Ghostscript rebuild the file structure from the command line, and Acrobat can save a repaired copy. If the data itself is missing, the only fix is a fresh copy.
Why does a PDF open on my computer but not on my phone?
The file is probably a large scan that exceeds the phone's browser memory. Compress it, or split it into smaller parts on a computer, then send those.