.NET file-based apps now default to .NET 11

Change effective on 11 November 2026

We’ve updated our .NET buildpacks to use .NET 11 (net11.0) by default for file-based apps that don’t specify a target framework.

File-based apps are single .cs source files without a project or solution file. Apps that explicitly set TargetFramework with a #:property directive or Directory.Build.props continue to use that configured target framework.

For example, to target .NET 10:

#:property TargetFramework=net10.0

Refer to .NET Behavior in Heroku for more details.