View PDF files in Firefox or choose another viewer

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To display PDF files inside the Firefox browser window, you can use the PDF Viewer extension or a PDF reader plugin. This article covers both methods and how to fix the common issues you might encounter.

Using the PDF Viewer extension

Note: This extension is still in Beta phase. If you are not comfortable with that, you should instead consider using a PDF reader plugin and skip down to this section.

PDF Viewer (aka pdf.js) is a new revolutionary extension using web standard technologies that allows you to display within Firefox almost all PDF files found on the web without a plugin.

PDF JS

As it's not very old, it has the following teething problems.

PDF files open with the PDF reader plugin instead of the extension

Enabling PDF Viewer is not enough so that Firefox uses it as the default PDF viewer. You need to disable every PDF reader plugins:

  1. Click the menu button Fx89menuButton, click Add-ons and themes and select Plugins.
  2. Select each PDF reader plugin and click Disable close to it.

Some PDF files don't render well or are blank

PDF Viewer may have some issues to render fonts, colors or the whole document in certain PDF files. Disable it temporarily so that the PDF file opens outside Firefox with your default PDF reader:

  1. Click the menu button Fx89menuButton, click Add-ons and themes and select Extensions.
  2. Select PDF Viewer and click Disable close to it.
    • When you're done, click Enable to use it again for other PDF files.

Cannot open any PDF files

Some extensions blocking JavaScript scripts may prevent PDF Viewer from viewing PDF files. Disable them:

  1. Click the menu button Fx89menuButton, click Add-ons and themes and select Extensions.
  2. Select each blocking extension and click Disable close to it.

For more information, see Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems.

Using a PDF reader plugin

If you can't deal with the PDF Viewer problems, you can still use PDF reader plugins like Adobe Reader, Nitro PDF Reader or Sumatra PDFAdobe Reader, MozPlugger, or KParts pluginSchubert|it PDF Browser Plugin on Mac OS X 10.6 and later or Firefox PDF Plugin extension.

PDF files are blank and can't be downloaded

When you install or update Adobe Reader, it installs a plugin for viewing PDF files inside Firefox and sets that as the default. The problem is that this plugin does not work. In order to view PDF files again follow these steps:

  1. In the Menu bar at the top of the screen, click Firefox and then select Preferences or Settings, depending on your macOS version.Click the menu button Fx89menuButton and select Settings.
  2. Select the Applications panel.
  3. Type pdf into the search bar.
  4. For each content type listed, click on the drop-down menu in the Action column and change the selection to use Adobe Reader, Preview or PDF Browser Plugin (if you are using the Schubert PDF plugin).
    Reader plugin - Mac
  5. Close the Settings page. Any changes you've made will automatically be saved.

Only the first page is visible (Mac 10.5 and below)

If PDF documents open within Firefox but only the first page is viewable, make sure that the QuickTime plugin isn't set to handle PDF content:

  1. From the Apple menu, choose System Preferences.
  2. From the View menu, choose QuickTime.
  3. Click the Plug-In tab and click MIME settings....
  4. In the list of MIME types, click the triangle next to "Images - Still image files".
  5. If "PDF Image" is checked, click the check box to clear it.
  6. Click OK

If you can't view a PDF in Firefox, continue with the next following instructions.

PDF files are downloaded

Check Firefox settings

  1. In the Menu bar at the top of the screen, click Firefox and then select Preferences or Settings, depending on your macOS version.Click the menu button Fx89menuButton and select Settings.
  2. Select the Applications panel.
  3. Find Adobe Acrobat Document (if you're using Adobe Reader) or PDF files (for other PDF readers) in the list and click on it to select it.
  4. Click on the drop-down arrow in the Action column for the above entry and select Use PDF reader name (in Firefox).
    Opening PDF - Win

    c77e7a43631723daa6760be30a717e46-1258906074-116-1.png
    • If Use PDF reader name (in Firefox) is not listed as an Option, see Reset download actions below and then repeat this set of instructions.
  5. Close the Settings page. Any changes you've made will automatically be saved.

If you still can't view a PDF in Firefox, continue with the following instructions.

Reset download actions

  1. Open your profile folder:

    • Click the menu button Fx89menuButton, click Help and select More Troubleshooting Information.From the Help menu, select More Troubleshooting Information. The Troubleshooting Information tab will open.
    • Under the Application Basics section next to Profile FolderDirectory, click Open FolderShow in FinderOpen Directory. A window will open that contains your profile folder.Your profile folder will open.
    Note: If you are unable to open or use Firefox, follow the instructions in Finding your profile without opening Firefox.

  2. Click the Firefox menu Fx89menuButton and select Exit.Click the Firefox menu at the top of the screen and select Quit Firefox.Click the Firefox menu Fx89menuButton and select Quit.
  3. Delete the mimetypes.rdf file.

Check Application settings

If the PDF reader plugin comes bundled with a reader application, check the application plugin setting if there is some.

  • Adobe Reader:
    1. Open Adobe Reader.
    2. Once in Adobe Reader, click the Edit menu in the menu bar, and then click Preferences... The Preferences window will open.
    3. In the Categories section, click on Internet.
    4. Make sure the first check box, Display PDF in browser, is checked.
    5. Click OK to dismiss the Preferences window, and then close Adobe Reader.

If you still can't view a PDF in Firefox, continue with the next following instructions.

Re-initialize the plugins database

Follow the instructions in the Re-initializing the plugins database section of the Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems article.

This will force Firefox to rebuild its plugin database. If you still can't view a PDF in Firefox, continue with the next following instructions.

Re-install the application

If the PDF reader plugin comes bundled with a reader application and the above troubleshooting methods for Firefox did not work, uninstall and re-install the application.

If you still can't view a PDF in Firefox, continue with the next following instructions.

Further information for Adobe Reader

If none of the above troubleshooting methods worked, see Can't view PDF on the web from Adobe.com for further instructions.