aspnetcore/breaking-changes/6/assemblies-removed-from-shared-framework.md
The following two assemblies were removed from the ASP.NET Core targeting pack:
In addition, the following assemblies were removed from the ASP.NET Core runtime pack:
ASP.NET Core 6.0
Applications could use APIs provided by these libraries by referencing the Microsoft.AspNetCore.App shared framework.
If you use APIs from the affected assemblies without having a PackageReference in your project file, you might see runtime errors. For example, an application that uses reflection to access APIs from one of these assemblies without adding an explicit reference to the package will have runtime errors. The PackageReference ensures that the assemblies are present as part of the application output.
For discussion, see https://github.com/dotnet/aspnetcore/issues/31007.
This change was introduced to reduce the size of the ASP.NET Core shared framework.
To continue using these APIs in your project, add a PackageReference. For example:
<PackageReference Include="System.Security.Permissions" Version="6.0.0" />