PDF attachments from application is not opening correctly. Adobe Reader spits this error message.
We use RDS 2012 R2 and Profile Disks for the users. Somehow PDF files on the profile disk is having same issue with Adobe Reader.
Solution: It turn out to be new Adobe Reader software has Protected Mode feature. This feature has issues with Profile Disks and Roaming profiles. Just disable Protected Mode under Security (Enhanced) section in Preferences.
Hope this helped you. Leave me a reply.