In SharePoint 2010, you may have noticed a bit of interesting behavior when trying to open a PDF file; we certainly did.  In fact, I’m surprised more people have not come across this in their 2010 environments, or perhaps the users simply thought this was the appropriate behavior and didn’t want to inform IT.

The issue is this: when you click on a PDF document to open it in your browser (or Adobe Reader) directly from SharePoint – it does not allow you to do this.  As you will notice in the screenshot below, there is no “Open” button as there should be.

As you can imagine, this defeats the purpose of SharePoint if you are required to save the file before opening it, and we simply had to discover why this was occurring.

We're in SharePoint daily, and we continually discover new settings, especially in Central Administration.  What we discovered is an additional security setting on the Web Application level, which instructs SharePoint to send information to the Web browser in an effort to restrict certain types of files from being opened directly; PDF is one of the file types restricted.  We suspect this may also depend on the specific browser as well, and we have not been able to find a definitive list of file types that could be affected by this.

Now that we know the issue, here's how to solve it:

1. Go to Central Administration and click on "Manage Web Applications"
2. Select the web application you would like to change, and select "General Settings"

3. Scroll down and you will see the "Browser File Handling" section
4. Select "Permissive"