Firefox 78: Set Firefox as the default PDF viewer on Windows

[harlan4096]

If you use the Firefox web browser to view PDF documents, you may have noticed that it is not possible to make it the default application for PDF files on Windows.

While you can open any PDF document in the Firefox web browser, it is not possible to associate the browser with the file type to load PDFs in the browser automatically, e.g. on double-click.

Firefox's installer does not associate PDF files with the browser, and that has been an intentional decision according to Mozilla.
 

The installer is responsible for registering support for default file associations on Windows. We've always intentionally left PDF out of that list, but that decision may be changing soon, so I'm moving this bug so that it can find its way into the installer team's planning.

Mozilla does not reveal why it has made the decision, but announced plans to change the handling of PDF file associations in Firefox 78, at least on Windows 10.

If you run Firefox 78 already, e.g. as a Nightly, Beta or Developer edition, you may be able to set Firefox as the default PDF handler already, e.g. when downloading a PDF document to the local system.

A new "open with" Firefox option should be displayed at the top and you may check the "Do this automatically for files like this from now on" option to automate the process and have Firefox open PDF documents automatically.

Firefox may also be associated with the PDF file type in Windows 10's Settings application. Just open Settings > Apps > Default Apps > Choose default apps by type, scroll down to PDF (why still no search on the page, Microsoft?), select PDF, and pick Firefox from the list of options to make the application the default PDF handler on the system.

Most Chromium-based browsers add themselves as the PDF handler on Windows 10 systems.

Closing Words

The addition of the option is a welcome change. While it may only be useful to a small set of Firefox users, those who want to set Firefox as the default PDF handler, it is a good move as its puzzling why Firefox is able to open PDF documents but cannot be set as the default program for the file type.

Firefox users who install the browser anew or upgrade the browser on Windows will benefit from the change.

I prefer to use a standalone PDF tool to view documents. Sumatra is my tool of choice provided that the PDF documents don't have advanced functionality that Sumatra does not support.

Now You: How do you open PDF documents?
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