How to have PDFs open in the default Windows 11 PDF App vs Firefox. Version 157

To set a specific application as the default for opening PDF files in Windows 11:

• Find any .pdf file on your computer.
• Right-click > Properties.
• On the "General" tab, next to the "Opens with" field, click the "Change" button.
• Select your preferred application from the list and click "Set default" or OK.

More info Change Default Apps in Windows

I have this same issue after the update to v157. Trying things with ChatGPT, it seems the cause is that the page is sending a response with: Content-Type: application/pdf; Content-Disposition: inline; filename=someName.pdf

So the Content-Disposition: inline is forcing the browser to open the pdf inline and not respect my preference to use Windows default app.

I checked several about:config options, and nothing fixed. Setting pdfjs.disabled = true makes the browser show a message like This PDF can't be displayed and a button to open it in the Windows app, but this requires an extra click to open it.

Direct links to pdf files work normally, respecting what I chose in settings.

I also tested in v156 again, it opens the same in pdf in Windows app. So the change was caused by v157. Both versions of Firefox have the same setting: open pdf in Windows app.

One detail: in my case, the page uses an iframe with the url for the pdf. In v156 it opens on Windows app; while v157 opens in Firefox.

This should be optional, I should decide how I want to open a pdf, not the site or the browser. This was the behavior in past versions, why change? This might make me stop using Firefox. It's the kind of forcing something to the user he doesn't want and not allowing him to change policy that made me leave Chrome before.

I prefer to use Foxit for pdf because I can place it's window side by side with Firefox, so I can see both a site I have to work on and the pdf; and also because I can chose how I see the pdf page (I prefer to show the full page, not a 100% zoom). In Firefox, the zoom is always automatic and I have to keep changing it.