Symptoms

The below error is seen when trying to deploy a process via K2 Designer for Visual Studio:

Error 1 Could not load file or assembly 'SourceCode.Security.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=16a2c5aaaa1b130d' or one of its dependencies. The system cannot find the file specified. C:ProjectsTransferPricingobjDebugDeploymentTransferPricing.msbuild 89 6 TransferPricing

However, deploying via K2 Studio is still possible.
 

Diagnoses

This seems to be related to how the K2 Designer for Visual Studio component was installed, and it may be corrupted.
 

Resolution

Reinstalling the component seems to resolve the issue. The following steps can be followed to reinstall the component:

1. Download a new version of the K2 installer from the K2 portal according to your version.
2. Move the zipped version of the combined installer directly to the machine you will be modifying the installation on.
3. Extract the installer file, and head over to the folder for K2 blackpearl rversion number]>Installation and run the Setup.exe.
4. Choose the "Modify" option and hit Next.
5. On the next screen, there should be a list of K2 components installed on the machine with check boxes next to them. Uncheck the checkbox next to the K2 Designer for Visual Studio component, and then hit Next through the installer until it starts configuring the installation.
6. Once the Modify has completed, restart your machine.
7. Once your machine has been restarted, rerun the same Setup.exe from the fresh K2 blackpearl installation media. Choose the "Modify" option again and hit Next
8. On the same screen of listed or available components, check the box next to the K2 Designer for Visual Studio component. This will effectively reinstall just that component, and repair the rest of the K2 core and client tools installation.
9. Reload your project in Visual Studio and try deploying to see if the error persists.