Hey, Have you tried going to Options>>General then navigate to 'Applications'. Now for 'PDF' recheck that Adobe Reader is set as default.

If you need to set up a specific download handler for your enterprise, check the Policy option:

• Customizing Firefox Using Group Policy (Windows)
• https://github.com/mozilla/policy-templates#handlers

That doesn't always work because servers may not send the official Content-Type ("application/pdf") with the file. But the workaround for that is too complicated to install on 1500 computers...

I did confirm that Adobe Reader is my default application for pdfs, thanks. I've also tried using the ADMX template (and disabling the pdfjs)--no luck. As to the handlers option, please forgive my ignorance, but could you possibly clarify how those options are actually deployed as registry keys? They look like portions of the handlers.json file, but I don't know how to create them as registry keys. Any help would be most appreciated. I've been tearing my hair out trying to make this go! Thanks!

I don't know the mechanics of how Firefox uses Policy settings to update or override handlers.json entries. Hopefully someone can answer that for you.

https://github.com/mozilla/policy-templates/blob/master/README.md#handlers

Has an example of how to set the Handler via ADMX.

It's some JSON you can add in the Handlers section.

I enabled the "Handlers" setting in the Firefox ADMX file and then pasted this into the "Options" area, but it didn't stop Firefox from prompting to either save or open in Adobe Reader:

{

 "mimeTypes": {
   "application/msword": {
     "action": "useSystemDefault",
     "ask": true | false
   }
 },
 "schemes": {
   "mailto": {
     "action": "useHelperApp",
     "ask": true | false,
     "handlers": [{
       "name": "Gmail",
       "uriTemplate": "https://mail.google.com/mail/?extsrc=mailto&url=%s"
     }]
   }
 },
 "extensions": {
   "pdf": {
     "action": "useHelperApp",
     "ask": "false",
     "handlers": [{
       "name": "Adobe Acrobat",
       "path": "C:\\Program Files (x86)\\Adobe\\Reader 11.0\\Reader\\AcroRd32.exe"
     }]
   }
 }

}

Hi hafenjodi, your reply was routed to the spam link moderation queue but it should appear here eventually.

How are you accessing the PDFs -- from a web server or from disk?

If the PDFs are being served by a web server, Firefox may ignore the instructions in handlers.json under certain circumstances based on the HTTP headers. These are the ones I'm most familiar with:

• Content-Disposition: attachment => as far as I know, Firefox always shows the download dialog
• Content-Type: (not application/pdf, and not application/octet-stream with a .pdf file extension) => Firefox doesn't treat the download as a PDF

Thanks for your reply, jscher2000. I'm accessing the pdf files from a web server (example, pdf links from this website: https://www.learningcontainer.com/sample-pdf-files-for-testing/). It does have a different content-type, but once I select "Open with Adobe Reader" and check the "always" box, it remembers it for the next time--leading me to think there's got to be SOME way to essentially check those boxes with Group Policy without touching every PC, right?

All three of those follow a similar pattern that triggers the download dialog:

https://www.learningcontainer.com/download/sample-pdf-file-for-testing/?wpdmdl=1566&refresh=6046ac5c4e80e1615244380

• content-disposition: attachment;filename="sample-pdf-file.pdf"
• content-type: application/pdf

I believe some sites do this without thinking much about it, while others do it to prevent viewing the PDF in a tab. Either way, Firefox doesn't have a built-in feature to override it, and I don't know whether you want to consider an extension for that or just let users interact with the dialog.

Note that you need to choose either true or false in: "ask": true | false,

• "ask": true,
• "ask": false,