Looks like the main issue is that the Html.Infragistics() helpers from older .NET MVC projects are not fully supported in .NET 6, since ASP.NET Core handles scripts and server-side helpers differently, which is why you’re seeing the Unexpected token '<' error—it usually happens when the server is returning HTML instead of JSON that the grid expects. In .NET 6, it’s recommended to use the jQuery-based approach with $.ig.Loader and $('#id').igGrid({...}), ensuring that your jQuery version matches the IgniteUI requirements and that all scripts are loaded in the correct order after jQuery. Also, double-check that your controller action is returning JSON properly via return Json(data) rather than a partial view when the grid expects data. For example, while working on performance monitoring tools like a PC Bottleneck Finder, ensuring the correct JSON response and script initialization sequence is key, and adopting the jQuery initialization method in ASP.NET Core will resolve the “Unexpected token '<'” issue efficiently.