Fixing Prompts When Opening PDFs in SharePoint 2010

A SharePoint 2010 environment had experienced a change in how SharePoint would open PDFs that lived in a Document Library. Previously, when someone clicked on a PDF, it would open right away in the web browser for them to view. Now, when someone clicked on a PDF, they would see the following prompt asking them if they would like to open the document in Read Only or Edit mode:

This behavior was not acceptable, as it was disruptive for people wanting to quickly access the contents of the PDF documents.

Source of the Change

When we tracked down the source of the change, we realized it was due to following Microsoft's KB on "SharePoint 2010 - Configuring Adobe PDF iFilter 9 for 64-bit platforms." In step 3, the article says that you need to add the following line to the DOCICON.XML file in the 14 Hive (/TEMPLATE/XML/):<Mapping Key="pdf" Value="pdf16.gif" /> This step is so that SharePoint will display the PDF icon in Document Libraries and other pages. However, this line is what caused the prompts to start appearing for end users.ResolutionTo stop the prompts from appearing, we needed to override the implicit OpenControl value from the previous change to the DOCICON.XML. We changed the line to the following:<Mapping Key="pdf" Value="pdf16.gif" OpenControl="" /> After performing an IISReset, end users were no longer seeing prompts when opening SharePoint hosted PDF documents. The PDFs would open right away in their web browser as before.