Cannot manage Active Directory Certificate Services.
The system cannot find the file specified. 0x80070002 (WIN32: 2 ERROR_FILE_NOT_FOUND)
This error is caused because you have not yet finished the configuration of AD CS using Windows Server 2012 R2 Server Manager. In previous versions of Windows Server, these installation steps were part of "adding the role", however in Server 2012 these additional configuration steps are hard to find and had me stumped.
To finish the configuration, click on AD CS on the left in server manager then hit the little "more" button that comes up. On the "All Servers Task Details and Notifications" select Configure Active Directory Certificate Services".
These have been marked in red in the following screenshot.
This is the only way using the GUI I could find to finish the installation. Hopefully this helps someone and safes some time, took me a good 10 minutes to figure this one out!