Recent answers to How do I enable the built-in pdf viewer and stop Firefox from using Acrobat Reader?https://support.mozilla.org/ar/questions/12214282018-11-01T16:54:40-07:00In case this comes up again, I created an extension that can help with this problem. I suggest leavi2018-11-01T16:54:40-07:00jscher2000https://support.mozilla.org/ar/questions/1221428#answer-1169170<p>In case this comes up again, I created an extension that can help with this problem. I suggest leaving it off until you run into a problem, and only turning it on (using its toolbar button) while you are downloading files that need it. Otherwise, because it intercepts every response from every web server, it may slow down your browsing.
</p><p><a href="https://addons.mozilla.org/firefox/addon/content-type-fixer/" rel="nofollow">https://addons.mozilla.org/firefox/addon/content-type-fixer/</a>
</p><p>If anyone tries it, let me know how it goes.
</p>ThePriusMan said
There is a totally simple explanation to this.
I read an article on the Mozilla S2018-06-14T08:54:40-07:00Jameshttps://support.mozilla.org/ar/questions/1221428#answer-1122769<p><em>ThePriusMan <a href="#answer-1121915" rel="nofollow">said</a></em>
</p>
<blockquote>
There is a totally simple explanation to this.
I read an article on the Mozilla Support Page and it says that Firefox Quantum <strong>will no longer be supporting NPAPI plugins like Adobe Flash, Shockwave Flash, and Silverlight</strong>, because there are more and more static pages on the internet, and I think that a solution to this problem is to downgrade to Firefox ESR or older. (but don't got back to those really old versions like 10.0) The page with the different versions of Firefox is <a href="https://ftp.mozilla.org/pub/firefox/releases/" rel="nofollow">https://ftp.mozilla.org/pub/firefox/releases/</a> . I recommend scrolling down to Firefox 52.0 and installing that.
You also may need to load the plugins manually, so you can access that page at <a href="https://support.mozilla.org/en-US/kb/npapi-plugins" rel="nofollow">https://support.mozilla.org/en-US/kb/npapi-plugins</a>
</blockquote>
<p>You do not need to have any NPAPI Plugins in order to read that npapi-plugins kb article.
</p><p>You misunderstood the article. Firefox <strong>52.0 and later Releases</strong> (including the current 60.0.2) <strong>does not allow any NPAPI Plugins to run except for the Flash Player Plugin</strong> (old name Shockwave Flash) from Adobe.
</p><p>The legacy Firefox <strong>52 ESR</strong> does allow other NPAPI Plugins to run besides the Flash Player. However on Windows you need the 32-bit Firefox as the Win64 Firefox 52 ESR (and Releases from 42.0 to 51.0) only allowed the Flash Player and Silverlight Plugins to run.
</p><p>Note the "Flash Player" (old name Shockwave Flash) and the "Shockwave (for director) Player" are two different Plugins. If it has Flash in the name then it is Flash Player.
</p><p>Flash Player
<a href="https://www.adobe.com/products/flashplayer.html" rel="nofollow">https://www.adobe.com/products/flashplayer.html</a>
</p><p>Shockwave (for director) Player
<a href="https://www.adobe.com/products/shockwaveplayer.html" rel="nofollow">https://www.adobe.com/products/shockwaveplayer.html</a>
</p>I tried a few public sights and it seems to be working. The one I am having issue with is secure, s2018-06-12T04:24:59-07:00chadfarnetihttps://support.mozilla.org/ar/questions/1221428#answer-1121921<p>I tried a few public sights and it seems to be working. The one I am having issue with is secure, so I will try to contact them directly. It must be an issue on their end.
</p>chadfarneti said
Those opened in a tab. I will contact the affected servers to see if there is an2018-06-12T04:19:35-07:00jscher2000https://support.mozilla.org/ar/questions/1221428#answer-1121918<p><em>chadfarneti <a href="#answer-1121911" rel="nofollow">said</a></em>
</p>
<blockquote>
Those opened in a tab. I will contact the affected servers to see if there is an issue on their end. I really appreciate all your effort.
</blockquote>
<p>If there is a public URL for a volunteer to test, we may be able to spot the reason that the PDF bypasses the viewer.
</p>
<hr>
<p><em>ThePriusMan <a href="#answer-1121915" rel="nofollow">said</a></em>
</p>
<blockquote>
I think that a solution to this problem is to downgrade to Firefox ESR or older.
</blockquote>
<p>Hi ThePriusMan, that may be what <em>you</em> want to do, but if you read the question again, it is about using the <strong>built-in PDF viewer</strong> and NOT about using Adobe Reader or the Adobe Acrobat plugin.
</p><p>Also, if the server is sending a content-type other than application/pdf, or is sending content-disposition: attachment, then Firefox wouldn't use the plugin, either, it will always show the download dialog.
</p>There is a totally simple explanation to this.
I read an article on the Mozilla Support Page and it 2018-06-12T04:13:23-07:00user1504726https://support.mozilla.org/ar/questions/1221428#answer-1121915<p>There is a totally simple explanation to this.
I read an article on the Mozilla Support Page and it says that Firefox Quantum will no longer be supporting NPAPI plugins like Adobe Flash, Shockwave Flash, and Silverlight, because there are more and more static pages on the internet, and I think that a solution to this problem is to downgrade to Firefox ESR or older. (but don't got back to those really old versions like 10.0) The page with the different versions of Firefox is <a href="https://ftp.mozilla.org/pub/firefox/releases/" rel="nofollow">https://ftp.mozilla.org/pub/firefox/releases/</a> . I recommend scrolling down to Firefox 52.0 and installing that.
</p><p>You also may need to load the plugins manually, so you can access that page at <a href="https://support.mozilla.org/en-US/kb/npapi-plugins" rel="nofollow">https://support.mozilla.org/en-US/kb/npapi-plugins</a>
</p>Those opened in a tab. I will contact the affected servers to see if there is an issue on their end2018-06-12T04:09:16-07:00chadfarnetihttps://support.mozilla.org/ar/questions/1221428#answer-1121911<p>Those opened in a tab. I will contact the affected servers to see if there is an issue on their end. I really appreciate all your effort.
</p>Is the problem with all PDFs or are only certain servers affected? For example, this old one definit2018-06-12T04:06:59-07:00jscher2000https://support.mozilla.org/ar/questions/1221428#answer-1121910<p>Is the problem with all PDFs or are only certain servers affected? For example, this old one definitely should open in a tab:
</p><p><a href="https://www.jeffersonscher.com/temp/Firefox%20Search%20Bar%20Show%20Engine%20Names%20(Firefox%2043)%20_20171004.pdf" rel="nofollow">Firefox Search Bar Show Engine Names (Firefox 43+) | Userstyles.org - Firefox Search Bar Show Engine Names (Firefox 43) _20171004.pdf</a>
</p>it was set to default. still not working. thanks for all your help. if you want to give up, i und2018-06-12T03:59:16-07:00chadfarnetihttps://support.mozilla.org/ar/questions/1221428#answer-1121906<p>it was set to default. still not working. thanks for all your help. if you want to give up, i understand.
</p>Mine has action 3 as well, so that looks correct to me.
If Firefox shows a blank tab for the PDF and2018-06-12T03:15:19-07:00jscher2000https://support.mozilla.org/ar/questions/1221428#answer-1121890<p>Mine has action 3 as well, so that looks correct to me.
</p><p>If Firefox shows a blank tab for the PDF and then immediately shows a Save dialog (bypassing the usual Open / Save / Cancel dialog), could you check this setting:
</p><p>(1) In a new tab, type or paste <strong>about:config</strong> in the address bar and press Enter/Return. Click the button promising to be careful or accepting the risk.
</p><p>(2) In the search box above the list, type or paste <strong>pdfjs</strong> and pause while the list is filtered
</p><p>(3) If the <strong>pdfjs.disabled</strong> preference is bolded and "modified" or "user set" to true, double-click it to restore the default value of false
</p>Does his look correct?
2018-06-12T02:12:47-07:00chadfarnetihttps://support.mozilla.org/ar/questions/1221428#answer-1121874<p>Does his look correct?
</p>So on the Preferences page you have Firefox set to
Portable Document Format (PDF) => "Preview in2018-06-12T01:50:07-07:00jscher2000https://support.mozilla.org/ar/questions/1221428#answer-1121865<p>So on the Preferences page you have Firefox set to
</p><p>Portable Document Format (PDF) =&gt; "Preview in Firefox"
</p><p>If Firefox doesn't follow that instruction, there are three typical explanations:
</p>
<ul><li> the server did not identify the file properly (the content-type is not specifically "application/pdf")
</li><li> the server instructed Firefox to force a download (the content-disposition was set to attachment)
</li><li> the handlers.json / mimeTypes.rdf file is corrupted with nonsense entries
</li></ul>Perhaps I am not explaining it correctly. I want the pdf to open in a webpage, not download and sav2018-06-12T01:35:13-07:00chadfarnetihttps://support.mozilla.org/ar/questions/1221428#answer-1121857<p>Perhaps I am not explaining it correctly. I want the pdf to open in a webpage, not download and save to my downloads folder. I click a link to a pdf in a website and instead of opening in firefox, it opens a box to download the file. If I click open from a different application and select firefox, it opens in a new window and still saves to my downloads folder.
</p>I just re-read your original post:
Open in Preview => should load in Apple's Preview app, if th2018-06-12T01:30:31-07:00jscher2000https://support.mozilla.org/ar/questions/1221428#answer-1121856<p>I just re-read your original post:
</p>
<ul><li> Open in Preview =&gt; should load in Apple's Preview app, if the server sent the document with the content-type "application/pdf"
</li></ul>
<ul><li> Preview in Firefox =&gt; should load in the built-in viewer, if the server sent the document with the content-type "application/pdf"
</li></ul>If Firefox stops obeying the Application settings listed on the Options page, you may need to remove2018-06-12T01:28:32-07:00jscher2000https://support.mozilla.org/ar/questions/1221428#answer-1121855<p>If Firefox stops obeying the Application settings listed on the Options page, you may need to remove a settings file and have Firefox regenerate it. Here's how:
</p><p>Open your current Firefox settings (AKA Firefox profile) folder using either
</p>
<ul><li> "3-bar" menu button &gt; "?" Help &gt; Troubleshooting Information
</li><li> (menu bar) Help &gt; Troubleshooting Information
</li><li> type or paste about:support in the address bar and press Enter/Return
</li></ul>
<p>In the first table on the page, on the Profile Folder row, click the "Show in Finder" button. If Finder highlights an icon with a semi-random name like a1b2c3d4.default, double-click it to display the contents of that profile folder.
</p><p>Leaving that window open, switch back to Firefox and Exit, either:
</p>
<ul><li> "3-bar" menu button &gt; Exit/Quit
</li><li> (menu bar) File &gt; Exit (or Firefox &gt; Quit)
</li></ul>
<p>Pause while Firefox finishes its cleanup, then:
</p>
<ul><li> rename <strong>handlers.json</strong> to something like <strong>handlersOLD.json</strong>
</li><li> if you see a file named <strong>mimeTypes.rdf</strong>, rename that one to <strong>mimeTypesOLD.rdf</strong>
</li></ul>
<p>Start Firefox back up again and it should revert to the default download handling settings, in this case, "Preview in Firefox" for PDFs. Any improvement?
</p>I had an update to install, restarted and the problem still exists.
2018-06-11T23:11:16-07:00chadfarnetihttps://support.mozilla.org/ar/questions/1221428#answer-1121816<p>I had an update to install, restarted and the problem still exists.
</p>Is the problem only on one particular site or does it affect ALL PDF files from all sources?
Have yo2018-06-11T07:20:41-07:00jscher2000https://support.mozilla.org/ar/questions/1221428#answer-1121642<p>Is the problem only on one particular site or does it affect ALL PDF files from all sources?
</p><p>Have you shut down your Mac and restarted it since this problem began?
</p>This just started happening today. It has worked flawlessly for the past 2 years...
2018-06-11T06:18:29-07:00chadfarnetihttps://support.mozilla.org/ar/questions/1221428#answer-1121612<p>This just started happening today. It has worked flawlessly for the past 2 years...
</p>It depends of the content-type header. If server says that browser must download the file, it will b2018-06-11T06:11:43-07:00TyDraniuhttps://support.mozilla.org/ar/questions/1221428#answer-1121611<p>It depends of the content-type header. If server says that browser must download the file, it will be downloaded, regardless of your setup.
</p>Yes. I I try to preview in firefox but it takes me to the download popup
2018-06-11T06:01:13-07:00chadfarnetihttps://support.mozilla.org/ar/questions/1221428#answer-1121610<p>Yes. I I try to preview in firefox but it takes me to the download popup
</p>chadfarneti said
I have changed it to open in preview in preferences, but it still tries to downlo2018-06-11T05:54:22-07:00TyDraniuhttps://support.mozilla.org/ar/questions/1221428#answer-1121607<p><em>chadfarneti <a href="#question-1221428" rel="nofollow">said</a></em>
</p>
<blockquote>
I have changed it to open in preview in preferences, but it still tries to download
</blockquote>
<p>But after downloading is the file opening in the Adobe Reader?
</p>