Symptoms

Deployment from k2 for visual studio failed with error. When deploying from visual Studio the following error was raised.
C:windowsMicrosoft.NetFrameworkv4.0.30319Workflow.targets(125,5): error : ‘string’ does not contain a definition for ‘IsNullOrWhiteSpace’

 

Diagnoses

We checked and ensured that the project target framework was set to V4.0
We then checked the project file itself (file.proj) and found that the .net Framework was set to V3.5 manually, on the TargetFrameworkVersion node. We proceeded to change this to v4.0. retried to build the solution and the build succeeded. Then we proceeded to deploy the solution which deployed successfully.

 

Resolution

The .proj file TargetFrameworkVersion was incorrectly edited previously and needed to be changed to match the version of the target Framework of the project in the Visual studio IDE. Once this version was changed and the version of the IDE and the .proj file was set to the same versions Build and deployment from within Visual Studio succeeded. We the proceeded and changed the Target framework in the Visual Studio IDE to V4.5 and the build was secessfull.