title: How to enable c# 7 features on Unity3D projects
body: <p>I wrote a new method in my Unity3D project (using Visual Studio 2017), and for that method I need C# 7 or greater. So I followed the instructions in <a href="http://www.c-sharpcorner.com/article/enabling-c-sharp-7-compilation-with-visual-studio-2017/" rel="noreferrer">this guide</a>.</p>
  
  <p>Now, when I try to open the project's properties, Visual Studio opens it, but then it suddenly closes right after opening. Now I can't even open project's properties.</p>
  
  <p>This is how it looks:</p>
  
  <p><img src="https://i.stack.imgur.com/TlEdJ.gif" alt="gif"></p>
  
  <p>Why am I getting the first and third errors? (the ones I showed in the gif)</p>