RevalidatingIdentityAuthenticationStateProvider [closed]

I am having a problem in my program.cs (a blazor project)!

I have this in the code but it is gray with red underline, i dont know how to enable it, do i need a specific using statement?I currently have these!

using Microsoft.AspNetCore.Components.Authorization;using Microsoft.AspNetCore.Identity;using Microsoft.EntityFrameworkCore;using MudBlazor.Services;using MyApp.Data;   

I hope you can help me here!

I stumbled upon it when my build wouldn't launch!