error MSB1001: Unknown switch - Visual Studio 2017 RC

Question

When compiling my solution in Visual Studio 2017 RC I get

C:\Code\src\MSBUILD : error MSB1001: Unknown switch.
  Switch: -

  For switch syntax, type "MSBuild /help"

On every project.

I can compile the solution using Visual Studio 2015. I have changed the build output to 'Diagnostic' and this is still all that I see.

Answer 1

Looks like it was lightweight solution load. I hit F4 on the solution and disabled lightweight load, closed VS and re opened the solution, and it works fine now.

I've just re-enabled lightweight load, and sure enough I get the same error - definitely lightweight load.