Hello Jaeho,

Kendo UI for jQuery and Telerik UI for ASP.NET MVC use the same themes. As of R1 2023 SP1 release (version 2023.1.314) the LESS themes are no longer supported and distributed (see the release notes). This is why you notice missing folders and CSS files with different names than before R1 2023 SP1. The SASS themes naming convention is different now, for example:  default-main.css (previously it was kendo.default-main.min.css).

Since the LESS themes are dropped, the additional folders and CSS files that these themes needed are no longer present.

We would recommend going through the LESS to SASS migration article: https://docs.telerik.com/aspnet-mvc/styles-and-layout/less-themes/less-themes-migration

For more details on the SASS themes, see the SASS themes documentation topics here: https://docs.telerik.com/aspnet-mvc/styles-and-layout/sass-themes/overview

As for the issue with the Project's Configuration Wizard not showing the themes, this is because our Visual Studio extension must be updated, so that it can properly work with the new naming convention and list the themes. You can find the latest version of the extension here: https://marketplace.visualstudio.com/items?itemName=TelerikInc.ProgressTelerikASPNETMVCVSExtensions

Close all Visual Studio instances, download the installer and run it. It will update the Visual Studio extension and you should be able to see the themes in the Wizard.

Regards,
Ivan Danchev
Progress Telerik