error building shader in linux

I have a working game that I wrote on my windows machine and I’ve copied the project across to a linux box I built (running mint with monodevelop and monogame+deps etc) and was surprised how out of the box my game appeared to be compiling - infact there is only one error.

The error is an unexpected error in the effects processor and its throwing a System.NotImplementedException but I have no idea what part of my (very simple) shader it feels is not implemented.

Here is a paste of my shader:

Any clues as to what it does not like?

The system MonoGame uses to build shaders depends on proprietary software that comes installed with Windows, so currently building shaders is only supported on Windows. However, @dellis1972 was kind enough to implement a Pipeline extension that can build shaders by sending it over to a Windows server he has running. The instructions for setting it up can be found here. You can also run the compilation service on your own server if you happen to have a Windows server set up.