Invalid object name 'dbo.AspNetUsers' in Asp.NET MVC 5 Entity Framework

In Visual Studio go to "Tools -> NuGet Package Manager -> Package Manager Console" and in console window (inside Visual Studio) execute "Update-Database" command

I have faced same problem, Here I was forget to call EnsureCreated(). After calling this method it will create all tables required by Identity.

Startup.cs

public void Configure(IApplicationBuilder app, IHostingEnvironment env, IServiceProvider serviceProvider)
{
        ...

        // Make sure we have the database
        serviceProvider.GetService<ApplicationDbContext>().Database.EnsureCreated();
}

Here is the shortest integration of Asp.NET Identity tables to your existing database.

1) Open new project or your existing project in Visual Studio (2015 or 2013). Open your Server Explorer and open your DefaultConnection.Find your Identity tables. (In WebConfig file, localDB connectionstring should be active. And your other existing Database's connection string should not be active.) Double Click your [AspNetRoles], [AspNetUserClaims], [AspNetUsers], [AspNetUserLogins] tables. And copy all of their SQL codes.

2) Open your existing database in your SQL Server Management Studio, right click your database and click New Query past here what you copied in 1st part. You will past something like that:

CREATE TABLE [dbo].[AspNetRoles] (
[Id]   NVARCHAR (128) NOT NULL,
[Name] NVARCHAR (256) NOT NULL,
CONSTRAINT [PK_dbo.AspNetRoles] PRIMARY KEY CLUSTERED ([Id] ASC)
);


GO
CREATE UNIQUE NONCLUSTERED INDEX [RoleNameIndex]
ON [dbo].[AspNetRoles]([Name] ASC);



CREATE TABLE [dbo].[AspNetUsers] (
[Id]                   NVARCHAR (128) NOT NULL,
[Email]                NVARCHAR (256) NULL,
[EmailConfirmed]       BIT            NOT NULL,
[PasswordHash]         NVARCHAR (MAX) NULL,
[SecurityStamp]        NVARCHAR (MAX) NULL,
[PhoneNumber]          NVARCHAR (MAX) NULL,
[PhoneNumberConfirmed] BIT            NOT NULL,
[TwoFactorEnabled]     BIT            NOT NULL,
[LockoutEndDateUtc]    DATETIME       NULL,
[LockoutEnabled]       BIT            NOT NULL,
[AccessFailedCount]    INT            NOT NULL,
[UserName]             NVARCHAR (256) NOT NULL,
CONSTRAINT [PK_dbo.AspNetUsers] PRIMARY KEY CLUSTERED ([Id] ASC)
);


GO
CREATE UNIQUE NONCLUSTERED INDEX [UserNameIndex]
ON [dbo].[AspNetUsers]([UserName] ASC);


CREATE TABLE [dbo].[AspNetUserRoles] (
[UserId] NVARCHAR (128) NOT NULL,
[RoleId] NVARCHAR (128) NOT NULL,
CONSTRAINT [PK_dbo.AspNetUserRoles] PRIMARY KEY CLUSTERED ([UserId] ASC, [RoleId] ASC),
CONSTRAINT [FK_dbo.AspNetUserRoles_dbo.AspNetRoles_RoleId] FOREIGN KEY ([RoleId]) REFERENCES [dbo].[AspNetRoles] ([Id]) ON DELETE CASCADE,
CONSTRAINT [FK_dbo.AspNetUserRoles_dbo.AspNetUsers_UserId] FOREIGN KEY ([UserId]) REFERENCES [dbo].[AspNetUsers] ([Id]) ON DELETE CASCADE
 );


GO
CREATE NONCLUSTERED INDEX [IX_UserId]
ON [dbo].[AspNetUserRoles]([UserId] ASC);


GO
CREATE NONCLUSTERED INDEX [IX_RoleId]
ON [dbo].[AspNetUserRoles]([RoleId] ASC);



CREATE TABLE [dbo].[AspNetUserLogins] (
[LoginProvider] NVARCHAR (128) NOT NULL,
[ProviderKey]   NVARCHAR (128) NOT NULL,
[UserId]        NVARCHAR (128) NOT NULL,
CONSTRAINT [PK_dbo.AspNetUserLogins] PRIMARY KEY CLUSTERED ([LoginProvider] ASC, [ProviderKey] ASC, [UserId] ASC),
CONSTRAINT [FK_dbo.AspNetUserLogins_dbo.AspNetUsers_UserId] FOREIGN KEY ([UserId]) REFERENCES [dbo].[AspNetUsers] ([Id]) ON DELETE CASCADE
);


GO
CREATE NONCLUSTERED INDEX [IX_UserId]
ON [dbo].[AspNetUserLogins]([UserId] ASC);



CREATE TABLE [dbo].[AspNetUserClaims] (
[Id]         INT            IDENTITY (1, 1) NOT NULL,
[UserId]     NVARCHAR (128) NOT NULL,
[ClaimType]  NVARCHAR (MAX) NULL,
[ClaimValue] NVARCHAR (MAX) NULL,
CONSTRAINT [PK_dbo.AspNetUserClaims] PRIMARY KEY CLUSTERED ([Id] ASC),
CONSTRAINT [FK_dbo.AspNetUserClaims_dbo.AspNetUsers_UserId] FOREIGN KEY ([UserId]) REFERENCES [dbo].[AspNetUsers] ([Id]) ON DELETE CASCADE
);


GO
CREATE NONCLUSTERED INDEX [IX_UserId]
ON [dbo].[AspNetUserClaims]([UserId] ASC);

If you forget the lines which starting with GO, you will exactly see the error which is in Title of this question. Run this query and wait for succesfully creation of tables. Your existing database is now ready for Identity features of Asp.NET MVC 5.

3) Open WebConfig in your Visual Studio. We will change connectionstring here. Write this:

 <add name="DefaultConnection" connectionString="Data Source=YOUR_SERVER_NAME;Initial Catalog=YOUR_DATABASE_NAME;Persist Security Info=True;User ID=YOUR_USER_ID;Password=YOUR_PASSWORD.;MultipleActiveResultSets=True;Application Name=EntityFramework"  providerName="System.Data.SqlClient"/>

Instead of localDB connection string. Which is this:

 <add name="DefaultConnection" connectionString="Data Source=(LocalDb)\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\aspnet-....mdf;Initial Catalog=aspnet-...;Integrated Security=True" providerName="System.Data.SqlClient" />

That's all you need to do. Run your project and Register. You can see your new user data in AspNetUsers table, in your existing database.

I go through same issue.
sometime user create customize class for membership hence asp.net dont create AspNetUsers table
example :

public class Member : IdentityUser
{
    Public int MemberID { get; set; }
    public string Name { get; set; }
    public string Family { get; set; }
    public string Password { get; set; }

}  

in this scenario ASP.NET create Member table and when user want to authenticate,ASP.NET search for AspNetUsers and did not find this table. this problem solved with add TableAttribute in begin of customized class

[Table("AspNetUsers")]
public class Member : IdentityUser
{
    Public int MemberID { get; set; }
    public string Name { get; set; }
    public string Family { get; set; }
    public string Password { get; set; }

}