MSBuild version 15 introduced the concept of "Directory.Build.props" files. From the docs:

• `Directory.Build.props` is a user-defined file that provides customizations to projects under a directory. This file is automatically imported from Microsoft.Common.props unless the property `ImportDirectoryBuildTargets` is set to false.

What is not stated here is that only one `Directory.Build.props` will be imported automatically. Imagine your project exists in the directory `C:\repo\src\foo\foo.csproj` and there exists a file in both `C:\repo\src\Directory.Build.props` and `C:\repo\Directory.Build.props` then only `C:\repo\src\Directory.Build.props` will be automatically included when building `C:\repo\src\foo\foo.csproj`. If you would like `C:\repo\Directory.Build.props` to be included as well, then `C:\repo\src\Directory.Build.props` will have to include `C:\repo\Directory.Build.props` like so:

``````<Project>
<Import Project="\$([MSBuild]::GetPathOfFileAbove('Directory.Build.props', '\$(MSBuildThisFileDirectory)../'))" />
</Project>
``````

This is documented here.