By default, Adobe Reader and Adobe Acrobat integrate with Internet Explorer and cause PDF files to open automatically in the browser.
This confirmation-less rendering of PDF files has enabled attackers to deliver Adobe Reader and Acrobat exploits via the internet automatically. The result is surreptitious malware that downloads to your computer.
Fortunately, there is an easy way to prevent Adobe Reader and Acrobat from automatically rendering PDF files in your browser. Make this one small tweak, and henceforth you'll be notified if a website tries to open a PDF in your browser.
How to Prevent Reader From Opening PDFs in IE
Open Adobe Reader or Adobe Acrobat.
Open the Edit > Preferences... menu from the menu bar or use the keyboard shortcut Ctrl + K to get there even quicker.
From the left pane, select Internet.
In the Web Browser Options, uncheck the box next to Display PDF in browser.
Choose the OK button to save and exit the settings window.
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. At this point my only alternative to Edge is to download the pdf and then open it with Adobe (no response yet from MS in answer to my follow-up question about Adobe settings). If Microsoft provided common functionality in the Edge reader, such as the ability to advance a document one page at a time and a search capability, I wouldn't need another company's browser.
This is not the only way to make Acrobat the default PDF program, by the way. Adobe leads you in through “Properties” on the right-click menu of a PDF file. You can also right-click on a PDF and choose Open With / Choose Program. That opens the window shown above, where you can browse to Acrobat. Google Chrome will open PDF files in a Chrome browser window. If you would rather open a PDF in Adobe Reader, you can follow these steps. Chrome Settings. Ensure that Adobe Reader is installed on the computer. In Chrome, go to the “Menu” icon, then choose “Settings“. Scroll to the bottom and select “Advanced“.
Do Not Open Pdf In Edge Browser
You may find that you are presented with a PDF download option, which you can decline.