As support has ended for .NET Framework 4.5, Appframe has been upgraded to new .NET Framework versions.
Winforms and assemblies used in winforms development has been upgraded to .NET 4.6.1 and assemblies used on web has been upgraded to .net 4.8. Refer to docs.microsoft.com for more details on changes.
Existing winform projects and assemblies does not need to be upgraded immediately but will continue to work after the update.
After applying the August update all developers need to download the latest development runtime in order to build and publish projects.
The next time a project is updated it needs to be updated to use the new .NET version in order to compile with the latest development runtime assemblies.
Download development runtime from the tools menu option in win projects:
Navigate to project properties and change target framework to .NET Framework 4.6.1.