Open PDFs in Adobe instead of in Google Chrome

Slightly simpler way with latest Chrome browser:

1. Navigate to: chrome://settings/content/pdfDocuments
2. Then set that to on.

1- Go to chrome://settings.

2- Click on "Privacy" --> "Content Settings".

3- At the bottom, click on: 
"PDF Documents" --> "Open PDF files in the default PDF viewer application".

This should solve the problem!

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PS:

1- Instead of 1 & 2, you can navigate to: chrome://settings/content

2- You can click on the file name's small (upside) arrow in the "Downloads bar" at the bottom, and, click on "Always open with system viewer". However, this works only for this downloaded file, not other downloads (it should be a bug though)!

3- After doing the above three steps, when you click on a file in the download bar, it first opens another tab and closes it quickly (another bug, which is a little annoying)! But then opens the file in your PDF viewer anyway.

4- Previously you could control this from chrome://plugins which is now removed from Chrome (57 and later versions). So you just ignore what you found on the web about chrome://plugins.

FYI for others: if you're okay with the Chrome PDF viewer, but want only downloaded PDFs to open in your external PDF viewer (Adobe Acrobat, Foxit Reader, etc.), you don't need to disable the Chrome PDF Viewer.

Always open PDFs using your system's viewer

Simply click the arrow next to a PDF download and select the option to use the system viewer.

Turn off auto-open of PDFs in the system viewer

UPDATE 6/7/2017

As of Chrome version 59, the option below doesn't exist in Settings. I'll leave these instructions, because if they ever add it back it'll probably be in the same place.

1. Click on the Chrome Menu icon
2. Click on
3. Scroll down and click
4. Scroll down to Downloads. If you have enabled any file types to open using the system viewer, you'll see a button to Clear auto-opening settings. Clicking this will reset the settings for all file types.

More info

Relevant SuperUser discussion here: How to automatically open "saved" pdfs in system viewer on chrome?

In Chrome, type chrome://plugins/
Find the Chrome PDF Viewer and click Disable
From your browser, click a PDF file; it should show at the bottom as a downloaded file.
Click the arrow next to the downloaded file, and choose Always open files of this type (You may need to manually click Open on any recent files you want to view, otherwise...)
The next time you click a PDF file, it should open however your computer is configured to open PDF files. If that method is via Adobe Reader or Adobe Acrobat (standard, pro), then that should meet the need you expressed in your question.

You should try this:

1. Open Chrome.
2. Type chrome://plugins/ in the address bar, hit enter.
3. Browse the list for Adobe PDF viewer or Adobe reader (and chrome pdf viewer)
4. Disable both (although disabling adobe reader would work alone.)

Hope this helps.