.NET Core 8首次EF迁移报错：服务构造失败+找不到DbContext

我有一个包含三个项目的解决方案：

• EmployeeManagement.Database：定义DbContext的类库
• EmployeeManagement.Entities：存放所有实体的类库
• EmployeeManagement.WebAPI：Web API项目

我尝试创建继承自IdentityDbContext的ApplicationDbContext，但在EmployeeManagement.WebAPI项目中执行dotnet ef migrations add InitialMigration命令时出现错误。错误信息包括：

• 访问Microsoft.Extensions.Hosting服务时出错，部分服务无法构造（无法解析System.TimeProvider、Microsoft.AspNetCore.DataProtection.IDataProtectionProvider）
• 在程序集'EmployeeManagement.WebAPI'中未找到DbContext

DbContext代码（EmployeeManagement.Database项目） #

public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
{
    public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options): base(options)
    {
    }

    public DbSet<ApplicationUser> ApplicationUsers { get; set; }
  
    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
    }
}

ApplicationUser类（EmployeeManagement.Entities项目） #

public class ApplicationUser : IdentityUser
{
}

Program.cs代码（EmployeeManagement.WebAPI项目） #

using EmployeeManagement.Database;
using EmployeeManagement.Entities;
using Microsoft.AspNetCore.Identity;
using Microsoft.EntityFrameworkCore;

var builder = WebApplication.CreateBuilder(args);

// 添加服务到容器
builder.Services.AddControllers();
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

builder.Services.AddDbContext<ApplicationDbContext>(options =>
    options.UseSqlServer(builder.Configuration.GetConnectionString("DefaultConnection")));

builder.Services.AddAuthorization();
builder.Services.AddIdentityCore<ApplicationUser>()
    .AddEntityFrameworkStores<ApplicationDbContext>()
    .AddApiEndpoints();

var app = builder.Build();

// 配置HTTP请求管道
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

app.MapIdentityApi<ApplicationUser>();

app.UseHttpsRedirection();
app.UseAuthorization();

app.MapControllers();

app.Run();

appsettings.json代码（EmployeeManagement.WebAPI项目） #

{
    "ConnectionStrings": {
        "DefaultConnection": "Server=localhost;Database=EmployeeManagementDb;Persist Security Info=True;User ID=PPPP;Password=PPPPPP;MultipleActiveResultSets=True;"
    },
    "Logging": {
        "LogLevel": {
            "Default": "Information",
            "Microsoft.AspNetCore": "Warning"
        }
    },
    "AllowedHosts": "*"
}

内容的提问来源于stack exchange，提问作者sara