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Unable to create an object of type 'ApplicationDbContext'. Add an implementation of 'IDesignTimeDbContextFactory<ApplicationDbContext>' to the project

I am trying to create an Angular 8 project with asp.net Core 2.1.
Whenever I try to add migration using command
cmd command: dotnet ef migrations add init --project ../Lgn.DAL
The terminal throws error :
Unable to create an object of type 'ApplicationDbContext'. Add an implementation of 'IDesignTimeDbContextFactory' to the project, or see https://go.microsoft.com/fwlink/?linkid=851728 for additional patterns supported at design time.
Startup.cs
``
public class Startup
{
public Startup(IConfiguration configuration)
{
Configuration = configuration;
}
public IConfiguration Configuration { get; }
// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
{
services.AddDbContext<ApplicationDbContext>(options =>
options.UseSqlite(Configuration.GetConnectionString("DefaultConnection")));
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}
// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
}
else
{
app.UseHsts();
}
app.UseCors(builder =>
{
builder.WithOrigins("http://localhost:4200");
builder.AllowAnyMethod();
builder.AllowAnyHeader();
});
app.UseHttpsRedirection();
app.UseMvc();
}
}``

Take a look at this solution to someone with a similar issue. Is your dependency injection setup all good? (number 2 on that list)
Here are the things to consider:
You get that error because to generate migrations you need either:
A DbContext with a default constructor (that is, a parameterless
constructor)
Being able to get the DbContext from ApplicationServices
(that is, Dependency Injection)
A design time factory that returns a
properly configured DbContext.

SignInManager dependency injection fails with ASP.NET Core 2

I'm trying to get access to Microsoft.AspNetCore.Identity.SignInManager in one of my classes that is not a controller.
In Startup.ConfigureServices() I have:
services.AddIdentity<IdentityUser, IdentityRole>();
In my class I have:
public class Auth : IAuth
{
...
private readonly SignInManager<IdentityUser> _signInManager;
public Auth(..., SignInManager<IdentityUser> signInManager)
{
}
}
And I get this exception:
An unhandled exception occurred while processing the request.
InvalidOperationException: Unable to resolve service for type
'Microsoft.AspNetCore.Identity.IUserStore1[Microsoft.AspNetCore.Identity.IdentityUser]'
while attempting to activate
'Microsoft.AspNetCore.Identity.AspNetUserManager1[Microsoft.AspNetCore.Identity.IdentityUser]'.
Notice I'm not even referencing the passed SignInManager object in the constructor (I was but have removed it to simplify). If I remove the SignInManager parameter from the constructor everything works fine.
All the relevant examples I have seen online end up being the case where the SignInManager's specified user data type in the call to AddIdentity() doesn't match the user data type in the constructor parameter, but that isn't the case in my code.
Reading articles and example code for this makes it seem like this should be a simple task. My constructor's other dependency injected parameters are working just fine except that I have the same issue if I try to inject RoleManager (except with a slightly different exception message).

While you have added Identity, you haven't configured any data stores. From the docs you should be doing something like this:
services.AddIdentity<ApplicationUser, IdentityRole>()
.AddEntityFrameworkStores<ApplicationDbContext>()
.AddDefaultTokenProviders();
If you are using ASP.Net Core 2.1 however, use the newer version:
services.AddDefaultIdentity<IdentityUser>()
.AddEntityFrameworkStores<ApplicationDbContext>();

User below if you are using asp.net core 3.18 version
services.AddDefaultIdentity<IdentityUser>()
.AddEntityFrameworkStores<ApplicationDbContext>();

Inject ApplicationDbContext into Configure method in Startup

I'm using EntityFrameworkCore 2.0.0-preview2-final and I would like to inject the ApplicationDbContext into Configure method in Startup class.
Here's my code:
public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory, ApplicationDbContext context)
{
// rest of my code
}
but when I run my app I'm getting an error message:
System.InvalidOperationException: Cannot resolve scoped service
'ProjectName.Models.ApplicationDbContext' from root provider.
Here's also my code from ConfigureServices method:
services.AddDbContext<ApplicationDbContext>(options =>
{
if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
{
options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection"));
}
else
{
options.UseSqlite("Data Source=travelingowe.db");
}
});
Do you have any idea how can I solve this problem?

This will work in 2.0.0 RTM. We've made it so that there is a scope during the call to Configure so the code you originally wrote will work. See https://github.com/aspnet/Hosting/pull/1106 for more details.

EF Core DbContext is registered with scoped lifestyle. In ASP native DI container scope is connected to instance of IServiceProvider. Normally when you use your DbContext from Controller there is no problem because ASP creates new scope (new instance of IServiceProvider) for each request and then uses it to resolve everything within this request. However during application startup you don't have request scope so you should create scope yourself. You can do it like this:
var scopeFactory = app.ApplicationServices.GetRequiredService<IServiceScopeFactory>();
using (var scope = scopeFactory.CreateScope())
{
var db = scope.ServiceProvider.GetRequiredService<ApplicationDbContext>();
// rest of your code
}
EDIT
As davidfowl stated this will work in 2.0.0 RTM since scoped service provider will be created for Configure method.

ASP.NET MVC 6 AspNet.Session Errors - Unable to resolve service for type?

Alright, so recently I've been having a lot of trouble using the new Microsoft.AspNet.Session middleware for ASP.NET vNext (MVC 6). The error I'm getting,
Unable to resolve service for type
'Microsoft.Framework.OptionsModel.ConfigureOptions[Microsoft.AspNet.Session.SessionOptions]
while attempting to activate
'Microsoft.AspNet.Session.SessionMiddleware'
occurs on all pages regardless of session use. The DNVM version I'm using is Beta5 x86 and all the packages in the project are Beta5 as well. The project itself is an attempt at porting an ASP.NET MVC 5 project to MVC 6 without much luck. Below are links to resources that may be important:
Project.json: http://tinyurl.com/project-json
Startup.cs: http://tinyurl.com/startup-cs
It seems to be a problem with my configuration but I'm not sure what to do about it... Pls send help Dx

Unable to resolve service for type 'Microsoft.AspNetCore.Session.ISessionStore' while attempting to activate 'Microsoft.AspNetCore.Session.SessionMiddleware'
If you get this error message in ASP.NET Core, you need to configure the session services in Startup.cs:
public void ConfigureServices(IServiceCollection services)
{
services.AddMvc()
.AddSessionStateTempDataProvider();
services.AddSession();
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
app.UseSession();
app.UseMvcWithDefaultRoute();
}

This code helps you...
In Startup.cs file
public void ConfigureServices(IServiceCollection services)
{
....
services.AddSession(options =>
{
options.IdleTimeout = TimeSpan.FromMinutes(30);//We set Time here
options.Cookie.HttpOnly = true;
options.Cookie.IsEssential = true;
});
...
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
app.UseSession();
app.UseMvc();
}
Thanks!!!

you can add session middleware into configure method in the startup.
public void ConfigureServices(IServiceCollection services) {
services.AddSession();
services.AddMvc();
}

Step 1: Install "Microsoft.AspNetCore.Session" this package.
Step 2: Add these functions in configure services function in the startup file.
(1). services.AddSession();
(2). services.AddDistributedMemoryCache();
Step 3: Add "app.UseSession()" use session function in Configure function in the startup file.

ASP.NET CORE 6.0
In program.cs file add this
builder.Services.AddDistributedMemoryCache();
builder.Services.AddSession(options =>
{
options.IdleTimeout = TimeSpan.FromSeconds(1800);
options.Cookie.HttpOnly = true;
options.Cookie.IsEssential = true;
});
Then
app.UseSession();
For more Read official doc

For ASP.NET 7 there is no longer a Startup.cs file, as it is merged with the Program.cs file. Instead add
builder.Services.AddSession();
builder.Services.AddDistributedMemoryCache();
above
var app = builder.Build();
Then you can add
app.UseSession();

I am using .net core 5 . I was getting the same issue
this is how i solved it
public void ConfigureServices(IServiceCollection services)
{
services.AddSession();
services.AddMvc();
}
I have added these and I have also added these ,
I added it to the startup.cs class
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
app.UseRouting();
}
My problem is solved, I hope yours is solved too.

app.usesession() in the program.cs file; I deleted your method and it was fixed

Unable to use session in ASP.Net vNext Project

I have an ASP.Net vNext project that uses Session. But I am getting this error while trying to get/set values in the session.
An exception of type 'System.InvalidOperationException' occurred in Microsoft.AspNet.Http.Core.dll but was not handled in user code
Additional information: Session has not been configured for this application or request.
Here's my controller method:
[AllowAnonymous]
[HttpGet("/admin")]
public IActionResult Index()
{
if (Context.Session.GetString("UserName") == null) // error thrown here
{
return RedirectToAction("Login");
}
return View();
}
I have added the KVM package "Microsoft.AspNet.Session": "1.0.0-beta3" in my project.json file as well and have configured my application to use session via my Startup.cs like so:
public void ConfigureServices(IServiceCollection services)
{
// code removed for brevity
services.AddCachingServices();
services.AddSessionServices();
}
public void Configure(IApplicationBuilder app)
{
app.UseMvc();
app.UseInMemorySession(configure: s => s.IdleTimeout = TimeSpan.FromMinutes(30));
}
I have looked at the vNext documentation on Github but it does not provide much information about ASP.Net sessions. What am I doing wrong?

So I figured this out. The fix was quite simple actually. Since ASP.Net adds the middlewares sequentially into the request pipeline, all I needed to do was use the session middleware before using MVC. More info here: https://stackoverflow.com/a/29569746/832546
Fixed code:
public void Configure(IApplicationBuilder app)
{
app.UseInMemorySession(configure: s => s.IdleTimeout = TimeSpan.FromMinutes(30));
app.UseMvc();
}

Thanks to #acrhistof the link helped.
So if you are using RC1:
add this these dependencies in project.json:
"Microsoft.AspNet.Session": "1.0.0-rc1-final",
"Microsoft.Extensions.Caching.Memory": "1.0.0",
in Startup.cs file:
public void ConfigureServices(IServiceCollection services)
{
services.AddCaching();
services.AddSession();
services.AddMvc();
}
and
public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
app.UseSession(); //outside of dev if (env.IsDevelopment())
....
}

It seems like things changed once again and the well-known ASP.NET session has to be configured differently in the rc1. (no UseInMemorySession() or other AppBuilder methods are related to Session, now it is added as a service).
In general Session has to be installed, configured, and then used. All these steps are quite new and somewhat unusual. Moreover, it depends on Cache:
Session is built on top of IDistributedCache, so you must configure
this as well, otherwise you will receive an error.
The quotation above is from ASP.NET 5 docs. All you need to do is described here: https://docs.asp.net/en/latest/fundamentals/app-state.html#installing-and-configuring-session.