Full disclosure:  I do have a ticket open with K2 on this, but I wanted to open it up to the user community to see if anyone had any ideas to help me get it resolved.

I worked with K2 installation services to deploy a fresh install of BlackPearl 4.6.2.

Whenever we try to deploy a process from the K2 Designer for SharePoint, the following error message is shown:

System.Exception: System.ArgumentNullException: Value cannot be null.
Parameter name: path1
at System.IO.Path.Combine(String path1, String path2)
at SourceCode.Workflow.Authoring.Process.EnsureRequiredReferences()
at SourceCode.Workflow.Authoring.Process..ctor()
at SourceCode.WebDesigner.Authoring.SharePoint.GenerateProcess.Generate(String UserName, Int32 ProcessID, String InputData, String ProcessXML, String ConnectionString)
at SourceCode.WebDesigner.Authoring.SharePoint.GenerateProcess.Generate(String UserName, Int32 ProcessID, String InputData, String ProcessXML, String ConnectionString)


The process does compile successfully. We have tried/verified the following:
1. We have given the app pool acc local admin permissions
2. We have executed the Activate K2 Features a couple of times
3. We have validated that the settings under the <sourcecode.configuration> tag in the machine.config file are correct in both the 32 and 64 bit .NET frameworks
4. Using K2 Studio on the same server (and different server) deploys successfully.
5. There are no entries in the K2 Server Log files.

This was a fresh installation of 4.6.2, K2 Server and Workspace on a single server, with 2 SharePoint Servers. One web front end and another app server with Central Admin. The K2 for SharePoint components have been installed on both before running the "Active all features" wizard.