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Firefox can no longer open PDF files

  • 9 replies
  • 2 have this problem
  • Last reply by 37MAC73

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All of a sudden Firefox can no longer open PDF files. Instead it tries to repeatedly to re-download them. Even when trying opening a PDF file, from my local explorer, into firefox it just tries to re-download the file.

My issue doesn't seem to have anything to do with Firefox Handler options. (It's currently set to "always ask" for PDF files, because if I set it to "preview in Firefox" or "Use Firefox" I just get an infinite loop of tabs trying to re-download the pdf). I've tried deleting the handler.json file, which also did not fix my issue.

Firefox just doesn't seem to be able to view PDF files anymore :/.

I'll try re-installing and report back if that resolves the issue.

All Replies (9)

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Re-installing did not fix the issue.

I've attached an image showing the dialogue box which pops up when attempting to open a local PDF file.

clicking 'OK' just proceeds to open another tab with the same dialogue box again.

Modified by Zander46

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re-installing and choosing the remove addons option fixed the issue.

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Great. Please Mark your Question Solved with Your solution so others can find it.

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Aaaand the problem is back again!

This time i've tried disabling all my Add-ons before reinstalling, but it hasn't worked.

So i guess i have to reinstall again...

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Is the Firefox PDF Viewer enabled if you check this on the about:config page?

  • about:config?filter=pdfjs
  • pdfjs.disabled = false

You should never select Firefox as the application to handle a file when you get an open with dialog.

For PDF files you can check the setting in "Options/Preferences -> General -> Applications". That should normally be "Preview in Firefox".

You can rename/remove handlers.json and delete mimeTypes.rdf if present in the Firefox profile folder with Firefox closed to reset all file actions.

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

Modified by cor-el

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The same thing is happening to me. I think it is because I checked the do this every time check box the last time I downloaded a PDF file. How do I uncheck the check box? It does not show up anymore. Please help. -MAC

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Hi MAC, when you say "the same thing", could you clarify what is happening?

To undo "do this every time," go to the Applications section of the Options/Preferences page and find

Portable Document Format (PDF)

Then select either

  • "Preview in Firefox" to use the built-in viewer (it has a download button its black toolbar)
  • "Always Ask" to always show the Open-or-Save download dialog and bypass the viewer

Note that Firefox only recognizes certain .pdf file as matching those instructions: the server needs to send the application/pdf Content-Type header to trigger your selected preference.

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Yes thank you it worked. I scrolled down in the General tab thingy of the about:preferences page and found the files and applications box. I scrolled down in that, found the PDF, and changed it from save file to preview in Firefox. Thanks!!! -MAC

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And thank you for your very quick response.