Recently I was deploying an update to a workflow when I received the following message.
Upon further investigation, the cause of the problem were the dll references I was using for deploying this particular code to this particular environment.
I had updated my Dynamics SDK to use the latest set of dlls (8.2.0.566) while the environment I had already deployed to was on (7.1.0001.3108). A few updated file references later and I was back in business – coding, registering, deploying and testing my code.