Hi, there is no check box. Do you mean the Drop Down Box where you have 4 Options ? Please Copy/Paste about:preferences to the Address Bar then go down to the Heading of Applications and find PDF in the left side then Click the Right Side and tell it what you want to do. https://support.mozilla.org/en-US/kb/applications-panel-set-how-firefox-handles-files

Please let us know if this solved your issue or if need further assistance.

Hi, There is check box of course. Please read carefully what I wrote before.

When you click on the website link to pdf file firefox ask what to do with file and there is option (checkbox) to remember what to do,. Please check attachment. Setting in preferences in second attachment. Sorry for Polish language but everything is identical also in other languages.

Hi, since can not read your language in the 1st pic, I have no idea where that is. As it is not around my version of 59.0.3

The 2nd pic box is correct.

Did you read the URL ? Did you perform anything that was in it ?

omg, really?

When you change in settings/preferences, for example PDF from open in Adobe Acrobat to "Ask what to do" and you click on some website link to PDF file firefox ask you what to do with the file and you receive exaclty this message as in attachment.

Weird, I just change the box to what ever setting I want and that is that. No confirmation box.

Hi kafebiwa, you can confirm that Firefox has gotten the message by checking the Application settings on the Options page.

• Windows: "3-bar" menu button (or Tools menu) > Options
• Mac: "3-bar" menu button (or Firefox menu) > Preferences
• Linux: "3-bar" menu button (or Edit menu) > Preferences
• Any system: type or paste about:preferences into the address bar and press Enter/Return to load it

Scroll down to the Files and Applications section and under Applications, there should be a box showing your download preferences.

"Portable Document Format (PDF)" corresponds to the content type application/pdf which is the standard content type sent by servers for PDFs. Does it say "Use Adobe Acrobat DC" (or other version) on the right side? If not, go ahead and switch it now.

Any improvement?

Unfortunately, some sites do not send application/pdf with PDF downloads. Firefox will not match up other content types with the saved setting for PDFs. That is a hard problem to work around.

There's also an occasional issue where the settings file that stores download preferences become corrupted with contrary settings. In that case, you can rename the file and have Firefox rebuild it. Here's how:

Open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" Help > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, on the Profile Folder row, click the "Open Folder" button. This should launch a new window listing various files and folders in Windows Explorer.

Leaving that window open, switch back to Firefox and Exit, either:

• "3-bar" menu button > Exit/Quit
• (menu bar) File > Exit (or Firefox > Quit)

Pause while Firefox finishes its cleanup, then rename handlers.json to something like handlersOLD.json. If you see a file named mimeTypes.rdf, rename that one to mimeTypesOLD.rdf.

Start Firefox back up again. You'll need to reselect "Use Adobe Acrobat" on the Options page. Then... success?

I didn't notice your screenshots before. This PDF is sent to me with the correct content type:

http://www.pdf995.com/samples/pdf.pdf

@jscher2000 I did this and nothing change. I changed handlers.json to different name, after reboot firefox generate new file but this not resolved problem. mimeTypes not exist in my profile directory.

To be clear, I try to explain one more time where is my problem. I made printscreen from english version of firefox (attachment)

I have correct settings in preferences - automatic open in Adobe Acrobat DC but every time when I click on link with pdf or website generate pdf I receiving anoying message popup with question what to do with file. When I click "OK" pdf opening in Adobe Acrobat but I would like to open pdf in Acrobat without this message every time. I marked checkbox "DO this automatically.." but it looks that this checkbox doesn't work. There is no difference after marked. In chrome everything is ok.

@jscher2000 there is also not difference from what link and what pdf file. I receiveng this every time. For example http://www.pdf995.com/samples/pdf.pdf

In my opinion firefox do not saved information about automaticly open file so my question is where to find problem?

The checkbox just tells Firefox to update the preference shown on the Options page from Always Ask to whatever you selected in the dialog. You can see that part works fine because your preference was saved in handlers.json and shows correctly on the Options page.

The problem is your Firefox is not following the saved instruction for PDF files (and possibly other files?). The mystery is why not.

Do you use any add-ons that change how downloading works, change the content-disposition, etc.? Any proxy server or other intermediary that might modify the download in any way?

I have only two addon: adblock and lastpass but no difference when I disable them.

I also do not use any proxy. In firefox connection settings I have "use system settings" but I also tried to change to "no proxy" but no difference. I use also chrome and on second browser I don't have such a problem

Maybe there is some setting we're not thinking of which causes Firefox to ignore saved instructions. Could you:

New Profile Test

This takes about 3 minutes, plus the time to test a couple PDFs (you can use links in this thread or find some through search).

Inside Firefox, type or paste about:profiles in the address bar and press Enter/Return to load it.

Click the Create a New Profile button, then click Next. Assign a name like May2018, ignore the option to relocate the profile folder, and click the Finish button.

After creating the profile, scroll down to it and click the Set as default profile button below that profile, then scroll back up and click the Restart normally button. (There are some other buttons, but please ignore them.)

Firefox should exit and then start up using the new profile, which will just look brand new. If Firefox asks about activating Extensions, close those tabs for now to get a clean test.

Does Firefox apply saved instructions for opening PDFs in Acrobat in the new profile?

When you are done with the experiment, open the about:profiles page again, click the Set as default profile button for your normal profile, then click the Restart normally button to get back to it.