Symptoms

Today when deploying a workflow to K2 Staging I get an error message that I've never seen before:

The "Message" task was not found. Check the following: 1) The name of the task in the
project file is the same as the name of the task class. 2) The task class is "public" and
implements the Microsoft.BuiId.Framework.ITask interface. 3) The task is correctly declared
With in the project file, or in the *.tasks files located in the "C:WindowsMicrosoft.NETFrameworkW4.0.30319" directory.
 

Diagnoses

Customer noticed that he could deploy the workflow from his machine. The issue only occurs with the developer’s. They also checked and found that the K2 blackpearl version on failing machine has older version.
 

Resolution

Upgrading K2 blackpearl to match the same version as K2 server resolved the issue.