Backup
It’s a good idea to make a complete backup of the contents of the web site folder before beginning the migration process, just in case you want to revert to the previous version.
Web.config
Custom “appsettings” in web.config are no longer supported. Previously defined settings in web.config need to be moved to options.json
Application pool
The web application no longer supports using a shared application pool. If you previously hosted with a shared pool, create a new dedicated application pool.
Plugins
If you have existing plugins, they must be recompiled for .NET 8. If you aren’t sure how to do this, you can consider using the Automatic Compilation feature.