c# 6.0 - Feature 'interpolated strings' is not available in C# 5. Please use language version 6 or greater

Question

There is a similar question to this here but I believe that involves a different cause.

I moved a class from a newer project into an older project. Both were targeting .net 4.6 however after the move I received the following error on build.

Feature 'interpolated strings' is not available in C# 5. Please use language version 6 or greater.

I tried setting my project to build with C# 6 in the properties window with no change.

Answer 1

I eventually found the place to change it. It seems sometimes when you update your targets framework version this does not get changed.