I just got a new computer and installed Unity 5.3.1 along with Visual Studio Community 2015 and the Visual Studio Tools for Unity that came in the installer. While doing the 2D Roguelike tutorial, I opened the BoardManager script to edit and I got this error message:

I tried looking online and on Microsoft’s website but I still have no idea how to fix this. Visual Studio still opens and I can still write the script fine, but intellisense seems to be disabled for Unity syntax and I can’t adjust the properties of the file in Visual Studio (some links said to add the .NET framework in properties, but since I can’t adjust the properties at all this doesn’t work, see picture below).

Should I reinstall the VSUTs? Is there another way I can fix this? I didn’t have this problem with Unity 5.2 on my old computer. Thanks for the help!
- Change it back to external tool = monodevelop (Unity → Edit → Preferences → External Tools).
- Open any script (monodevelop will open it).
- Go to Project → Assembly-CSharp Options → General,
- and change Target framework to e.g. 4.5.2.
- change it to external tool = visual studio (Unity → Edit → Preferences → External Tools).
inspired by this , answer of alexzzzz
You need to install .Net Framework 3.5 for the profiles added by VSTU to become usable.
In Unity (2017.1) Goto BuildSettings → Players Settings → Other Settings → configuration and choose your desired scripting runtime version.