Sharepoint 2010 error opening .pdf files

When you try to open a PDF document from your standard SharePoint library, as it tries to open it in Acrobat viewer and you encounter the error:

There was an error opening this document. The filename, directory name, or volume label syntax is incorrect.

You can fix it read below:

DON'T

• Change Client Integration
• Change File handling methods

DO

Go to the following Path:

C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\TEMPLATE\XML

Edit the DOCICON.XML file 

Find this entry

<Mapping Key="pdf" Value="icpdf.png" OpenControl="PdfFile.OpenDocuments"/>

and edit it to 

<Mapping Key="pdf" Value="icpdf.png" OpenControl="SharePoint.OpenDocuments"/>

Hope this fixes your problem

Display / Show PDF icon in Sharepoint / MOSS

1. Copy the .gif file that you want to use for the icon to the following folder on the server, as appropriate for your version of SharePoint:
   SharePoint Portal Server 2003 - Drive:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\60\Template\Images
   SharePoint Server 2007- Drive:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\Template\Image
   SharePoint Server 2010 - Drive:\Program Files\Common Files\Microsoft Shared\Web server extensions\14\Template\Images
2. Stop IIS at a command prompt by running IISReset /stop
3. Edit the Docicon.xml file to include the .pdf extension. To do this, follow these steps:
   1. Start Notepad, and then open the Docicon.xml file. The Docicon.xml file is located in one of the following folders on the server:
      SharePoint Portal Server 2003 - Drive:\Program Files\Common Files\Microsoft Shared\Web server extensions\60\Template\Xml
      SharePoint Server 2007- Drive :\Program Files\Common Files\Microsoft Shared\Web server extensions\12\Template\Xml
      SharePoint Server 2010- Drive:\Program Files\Common Files\Microsoft Shared\Web server extensions\14\Template\Xml
   2. Add an entry for the .pdf extension. For example, add a line that is similar to the following to the Docicon.xml file, where NameofIconFile is the name of the .gif file:
      <Mapping Key="pdf" Value="NameofIconFile.gif"/>
   3. On the File menu, click Save, and then quit Notepad.
4. Start IIS at a command prompt by running IISReset /start