Phidgets.Bridge is not available in the target framework

[DenisFerrari]

Hi,
after few days working on a VS2017 1046 Bridge project, now every time I open forms using the Bridge, I have an error saying : "Type Phidgets.Bridge is not available in the target framework".

Using .NET Framework 4, tried 4.5, same issue.

Strange thing is that I did not have it until yesterday and I did not do anything particular.

If I Ignore the error, Forms can be opened and worked with and app seems working , but I'd like to understand how to solve it.

Any help ?

Thank you very much.