This was bugging me for some time... Both SwapBuffers() and wglSwapLayerBuffers() generate GL_INVALID_ENUM on first call.
Debug output from CodeXL says:
OpenGL Debug Output: API - Error, Using glGetString in a Core context with parameter <name> and enum '0x1f03' which was removed from Core OpenGL (GL_INVALID_ENUM)
Is this a driver bug? Or a Windows 10 bug? (I don't remember of this happening on win7)