It sounds like you were using Firefox's builtin PDF viewer instead of the PDF program that you have installed on your computer. You can change this by going to the Firefox settings and scrolling down to the Applications section. In that section, there should be a Portable Document Format (PDF) content type.

You will be given the option what to do with the file. The Open in Firefox option will open the PDF in Firefox, which sounds like the option that you are looking for. There are other options to choose as well, such as Save File or open with other applications installed on your computer.

Hope this helps.

Thanks, Wesley. If I have the setting for portable document format set to Firefox, nothing changes. And the setting for PDF file will not accept Firefox and keeps Adobe. Interesting, it will accept the Edge browser. My Firefox is up-to-date with 77.0.1 version (64-bit).

So, if I open a PDF file on my desktop, it just opens the file with Adobe. If I am at a website and download a pdf file, I get the Adobe question box to save or open the PDF file.

The problem with Edge is that it always controls the PDF file with their Microsoft tool. It seems people are pretty angry about that, they have paid subscriptions to some Adobe products that are hard to use with Edge. Not sure why they stay with Edge.

I now get the Open with Firefox as the first choice for my PDFs. GREAT. Thank you.

Thanks, Wesley. If I have the setting for portable document format set to Firefox, nothing changes. And the setting for PDF file will not accept Firefox and keeps Adobe. Interesting, it will accept the Edge browser. My Firefox is up-to-date with 77.0.1 version (64-bit). So, if I open a PDF file on my desktop, it just opens the file with Adobe. If I am at a website and download a pdf file, I get the Adobe question box to save or open the PDF file. The problem with Edge is that it always controls the PDF file with their Microsoft tool. It seems people are pretty angry about that, they have paid subscriptions to some Adobe products that are hard to use with Edge. Not sure why they stay with Edge.

Thanks, Wesley. If I have the setting for portable document format set to Firefox, nothing changes. And the setting for PDF file will not accept Firefox and keeps Adobe. Interesting, it will accept the Edge browser. My Firefox is up-to-date with 77.0.1 version (64-bit). So, if I open a PDF file on my desktop, it just opens the file with Adobe. If I am at a website and download a pdf file, I get the Adobe question box to save or open the PDF file. The problem with Edge is that it always controls the PDF file with their Microsoft tool. It seems people are pretty angry about that, they have paid subscriptions to some Adobe products that are hard to use with Edge. Not sure why they stay with Edge.

I now get the Open with Firefox as the first choice for my PDFs. GREAT. Thank you.

Yes, this is one of the new features of Firefox 78; it helps users with sites that try to force a PDF download instead of allowing it to just open in a tab.

Hello everione. About PDFs I chose to be asked every time. I need to save most PDFs or to open and edit them, but Firefox's default choice is to open them within the brouwser and that doesn't work for me :( I really dislike this last update's feat. Any chance I can get around this? thanks to all.

Firefox 78+ releases offers a choice to open PDF files that would normally be saved or opened in an external application in Firefox.
See "What's New" in the "3-bar" Firefox menu button drop-down list.

You can control this feature via a pref on the about:config page.

• browser.helperApps.showOpenOptionForPdfJS = false

You can open the about:config page via the location/address bar. You can accept the warning and click "I accept the risk!" to continue.

• https://support.mozilla.org/en-US/kb/about-config-editor-firefox

maronestore - I am asked every time. The first choice is open with Firefox, but I still have all the other choices like save, etc.

About PDFs I chose to be asked every time. I need to save most PDFs or to open and edit them, but Firefox's default choice is to open them within the brouwser and that doesn't work for me :(

Do you mean Firefox usually fills in the first bubble here:

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I don't know how Firefox chooses the default bubble in that dialog. There is a preference to hide that first option if you never expect to use it (browser.helperApps.showOpenOptionForPdfJS).