TeamCity fails to build projects using C# 7

Question

TeamCity is throwing errors when I added new the output variable syntax in our latest code update:

if (Enum.TryParse(input, out MyProject.ClassificationType classification))
{
    result.Classification = classification;
}

TeamCity threw this error:

[Csc] MyProject\MyCode.cs(125, 111): error CS1003: Syntax error, ',' expected

The code builds and runs fine in Visual Studio.

Answer 1

MSBuild on the TeamCity Agent's machine was outdated to using Microsoft Build Tools 2015.

I was able to fix this by downloading and installing the new Build Tools for Visual Studio 2017 found here:

https://www.visualstudio.com/downloads/ -> Other Tools and Frameworks -> Build Tools for Visual Studio 2017 -> Download

Or bypass the spam by going here: https://www.visualstudio.com/thank-you-downloading-visual-studio/?sku=BuildTools&rel=15

Update TeamCity's build step to build using MSBuild 15 or Visual Studio 2017.

Answer 2

Install the Build Tools for Visual Studio 2017 as suggested by Kcoder, adjust the build step in Team City afterwards (Example):

In case you use MSBuild as the build step, you can adjust similar settings.