Unable to create migrations after upgrading to ASP NET Core 2 0

Question

After upgrading to ASP NET Core 2 0  I can t seem to create migrations anymore   I m getting       An error occurred while calling method  BuildWebHost  on class    Program   Continuing without the application service provider  Error    One or more errors occurred   Cannot open database       requested by   the login  The login failed  Login failed for user          and      Unable to create an object of type  MyContext   Add an implementation   of  IDesignTimeDbContextFactory  to the project  or see   https   go microsoft com fwlink  linkid 851728 for additional patterns   supported at design time     The command I previously ran was   dotnet ef migrations add InitialCreate --startup-project     Web   from the project folder with the DBContext    Connection string   Server  localdb   mssqllocaldb Database database Trusted Connection True MultipleActiveResultSets true   This is my Program cs   public class Program       public static void Main string   args                BuildWebHost args  Run               public static IWebHost BuildWebHost string   args    gt         WebHost CreateDefaultBuilder args              UseStartup lt Startup gt                Build

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You also can use in the startup class constructor to add json file  where the connection string lies  to the configuration  Example       IConfigurationRoot  config      public Startup IHostingEnvironment env                var builder   new ConfigurationBuilder                SetBasePath env ContentRootPath               AddJsonFile  appsettings json              config   builder Build

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No need for IDesignTimeDbContextFactory   Run   add-migration initial -verbose   that will reveal the details under      An error occurred while accessing the IWebHost on class  Program   Continuing without the application service provider     warning  which is the root cause of the problem   In my case  problem was  having ApplicationRole   IdentityRole lt int gt  and invoking services AddIdentity lt ApplicationUser  IdentityRole gt    which was causing below error  System ArgumentException  GenericArguments 1    Microsoft AspNetCore Identity IdentityRole    on  Microsoft AspNetCore Identity EntityFrameworkCore UserStore 9 TUser TRole TContext  TKey TUserClaim TUserRole TUserLogin TUserToken TRoleClaim   violates the constraint of type  TRole   --- gt  System TypeLoadException  GenericArguments 1    Microsoft AspNetCore Identity IdentityRole    on  Microsoft AspNetCore Identity UserStoreBase 8 TUser TRole TKey TUserClaim  TUserRole TUserLogin TUserToken TRoleClaim   violates the constraint of type parameter  TRole

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First of all make sure you have configured your database in Startup cs In my case  i was getting this error since i didn t specify the below in Startup cs       services AddDbContext lt ApplicationDbContext gt  options   gt          options UseSqlServer              Configuration GetConnectionString  DefaultConnection    x   gt  x MigrationsAssembly   lt Your Project Assembly name where DBContext class resides gt

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In my case setting the StartUp project in init helps  You can do this by executing    dotnet ef migrations add init -s    StartUpProjectName

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In my case I got the problem because I had a method named SeedData EnsurePopulated   being called on my Startup cs file   public class Startup       public Startup IConfiguration configuration    gt  Configuration   configuration      public IConfiguration Configuration   get         public void ConfigureServices IServiceCollection services                              public void Configure IApplicationBuilder app  IHostingEnvironment env                app UseDeveloperExceptionPage            app UseStatusCodePages            app UseStaticFiles            app UseSession            app UseMvc routes   gt                                                SeedData EnsurePopulated app             The work of SeedData class is to add initial data to the database table  It s code is   public static void EnsurePopulated IApplicationBuilder app                ApplicationDbContext context   app ApplicationServices GetRequiredService lt ApplicationDbContext gt             context Database Migrate            if   context Products Any                          context Products AddRange              new Product                               Name    Kayak                   Description    A boat for one person                   Category    Watersports                   Price   275                                                            context SaveChanges                      SOLUTION  Before doing migration simply comment out the calling of SeedData class in the Startup cs file      SeedData EnsurePopulated app     That solved my problem and hope your problem is also solved in the same way

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In the AppContext cs besides AppContext class add another class      required when local database deleted public class ToDoContextFactory   IDesignTimeDbContextFactory lt AppContext gt        public AppContext CreateDbContext string   args                var builder   new DbContextOptionsBuilder lt AppContext gt               builder UseSqlServer  Server localhost Database DbName Trusted Connection True MultipleActiveResultSets true            return new AppContext builder Options             This will solve your second problem       Unable to create an object of type  MyContext   Add an implementation of  IDesignTimeDbContextFactory  to the project    After that you will be able to add-migration Initial and execute it by running update-database command  However if running these commands when there is no DataBase yet in your local SqlServer you will get the warning like your first error   An error     occurred while calling method  BuildWebHost  on class  Program     The   login failed  Login failed for user          But it is not error because migration will be created and it can be executed  So just ignore this error for the first time  and latter since Db will exist it won t happen again

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please verify that you have the reference   lt PackageReference Include  Microsoft EntityFrameworkCore Design  Version  2 0 0    gt

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You can add a class that implements IDesignTimeDbContextFactory inside of your Web project   Here is the sample code   public class DesignTimeDbContextFactory   IDesignTimeDbContextFactory lt CodingBlastDbContext gt        public CodingBlastDbContext CreateDbContext string   args                IConfigurationRoot configuration   new ConfigurationBuilder                SetBasePath Directory GetCurrentDirectory                 AddJsonFile  appsettings json                Build            var builder   new DbContextOptionsBuilder lt CodingBlastDbContext gt             var connectionString   configuration GetConnectionString  DefaultConnection            builder UseSqlServer connectionString           return new CodingBlastDbContext builder Options             Then  navigate to your Database project and run the following from command line   dotnet ef migrations add InitialMigration -s    Web   dotnet ef database update -s    Web   -s stands for startup project and    Web  is the location of my web startup project    resource

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public class Program       public static void Main string   args                BuildWebHost args  Run               public static IWebHost BuildWebHost string   args    gt          WebHost CreateDefaultBuilder args               UseStartup lt Startup gt                 Build              Just rename BuildWebHost   to CreateWebHostBuilder    because migrations use this method by default

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In my case  the cause of the problem was multiple startup projects  I have three projects in my solution  Mvc  Api  and Dal  DbContext and Migrations in the Dal project   I had configured multiple startup projects  Both Mvc and Api projects were running when I clicked Start  But in this case I was getting this error       Unable to create an object of type  MyContext   Add an implementation   of  IDesignTimeDbContextFactory  to the project  or see   https   go microsoft com fwlink  linkid 851728 for additional patterns   supported at design time     I could successfully add migration after setting Mvc as the only startup project and selecting Dal in the Package Manager Console

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If you want to avoid those IDesignTimeDbContextFactory thing  Just make sure that you don t use any Seed method in your startup  I was using a static seed method in my startup and it was causing this error for me

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From  https   docs microsoft com en-us ef core miscellaneous cli dbcontext-creation     When you create a new ASP NET Core 2 0 application  this hook is   included by default  In previous versions of EF Core and ASP NET Core    the tools try to invoke Startup ConfigureServices directly in order to   obtain the application s service provider  but this pattern no longer   works correctly in ASP NET Core 2 0 applications  If you are upgrading   an ASP NET Core 1 x application to 2 0  you can modify your Program   class to follow the new pattern    Add Factory in  Net Core 2 x  public class BloggingContextFactory   IDesignTimeDbContextFactory lt BloggingContext gt                public BloggingContext CreateDbContext string   args                        var optionsBuilder   new DbContextOptionsBuilder lt BloggingContext gt                 optionsBuilder UseSqlite  Data Source blog db                 return new BloggingContext optionsBuilder Options

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I was facing the error   Unable to create an object of type  MyContext   Add an implementation of  IDesignTimeDbContextFactory  to the project  or see https   go microsoft com fwlink  linkid 851728 for additional patterns supported at design time    This is how my problem was solved  Run the below command while you are in your solution directory   dotnet ef migrations add InitialMigration --project  Blog Infrastructure  --startup-project  Blog Appication    Here Application is my startup project containing the Startup cs class  amp  Infrastructure is my project containing the DbContext class   then run update using the same structure   dotnet ef database update --project  Blog Infrastructure  --startup-project  Blog Application

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For me the problem was that I was running the migration commands inside the wrong project  Running the commands inside the project that contained the Startup cs rather than the project that contained the DbContext allowed me to move past this particular problem

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Sample DB context class for  net core console applications  using Microsoft EntityFrameworkCore  using Microsoft EntityFrameworkCore Design  using Microsoft Extensions Configuration  using System IO   namespace EmailServerConsole Data       public class EmailDBContext   DbContext               public EmailDBContext DbContextOptions lt EmailDBContext gt  options    base options              public DbSet lt EmailQueue gt  EmailsQueue   get  set               public class ApplicationContextDbFactory   IDesignTimeDbContextFactory lt EmailDBContext gt                EmailDBContext IDesignTimeDbContextFactory lt EmailDBContext gt  CreateDbContext string   args                        IConfigurationRoot configuration   new ConfigurationBuilder                    SetBasePath Directory GetCurrentDirectory                     AddJsonFile  appsettings json                    Build                var builder   new DbContextOptionsBuilder lt EmailDBContext gt                 var connectionString   configuration GetConnectionString  connection string                builder UseSqlServer connectionString               return new EmailDBContext builder Options

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There s a problem with ef seeding db from Startup Configure in 2 0     you can still do it with this work around  Tested and worked fine  https   garywoodfine com how-to-seed-your-ef-core-database

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I had this issue in a solution that has    a  NET Core 2 2 MVC project  a  NET Core 3 0 Blazor project The DB Context in a  NET Standard 2 0 class library project   I get the  unable to create an object     message when the Blazor project is set as the start up project  but not if the MVC project is set as the startup project   That puzzles me  because in the Package Manager Console  which is where I m creating the migration  I have the Default project set to a the C  class library that actually contains the DB Context  and I m also specifying the DB context in my call to add-migration add-migration MigrationName -context ContextName  so it seems strange that Visual Studio cares what startup project is currently set     I m guessing the reason is that when the Blazor project is the startup project the PMC is determining the version of  NET to be Core 3 0 from the startup project and then trying to use that to run the migrations on the  NET Standard 2 0 class library and hitting a conflict of some sort   Whatever the cause  changing the startup project to the MVC project that targets Core 2 2  rather than the Blazor project  fixed the issue

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For me it was because I changed the Output Type of my startup project from Console Application to Class Library   Reverting to Console Application did the trick

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Previously  you configured the seed data in the Configure method in Startup cs  It is now recommended that you use the Configure method only to set up the request pipeline  Application startup code belongs in the Main method   The refactored Main method  Add the following references to the Program cs   using Microsoft Extensions DependencyInjection   using MyProject MyDbContextFolder    x000D   x000D  public static void Main string   args  x000D    x000D      var host   BuildWebHost args   x000D   x000D      using  var scope   host Services CreateScope    x000D        x000D          var services   scope ServiceProvider  x000D          try x000D            x000D              var context   services GetRequiredService lt MyDbConext gt     x000D              DbInitializer Initialize context   x000D            x000D          catch  Exception ex  x000D            x000D              var logger   services GetRequiredService lt ILogger lt Program gt  gt     x000D              logger LogError ex   An error occurred while seeding the database     x000D            x000D        x000D   x000D      host Run    x000D    x000D   x000D   x000D

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I had this problem and this solved By Set -  Web Application Included Program cs  Project to -   Set as Startup Project   Then run -  add-migration initial -verbose   in Package Manager Console  Set as Startup Project

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You can try this solution from this discussion  which was inspired by this post    public static IWebHost MigrateDatabase this IWebHost webHost        using  var scope   webHost Services CreateScope                  var services   scope ServiceProvider           try                       var db   services GetRequiredService lt MyContext gt                 db Database Migrate                      catch  Exception ex                        var logger   services GetRequiredService lt ILogger lt Program gt  gt                 logger LogError ex   An error occurred while migrating the database                          return webHost    public static void Main string   args        BuildWebHost args           MigrateDatabase            Run

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Manzur Alahi is right  I m trying to learn Rider by JetBrains and I had the same error when I was trying to use dotnet-ef migrations add      in Cmd  PowerShell  etc  but when I used Visual Studio IDE I didn t have problem  I fixed the error with  dotnet ef migrations add InitialMigration --project  quot Domain Entities quot  --startup-project  quot WebApi quot   and this to update the database dotnet ef database update --project  quot Domain Entities quot  --startup-project  quot WebApi quot   just like Manzur Alahi  said

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In main project s appsettings json file  I had set  Copy to Output directory  to  Copy always  and it worked

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Something that really helped me was this article  https   elanderson net 2017 09 unable-to-create-an-object-of-type-applicationdbcontext-add-an-implementation-of-idesigntimedbcontextfactory   The basic idea is that in the change over from  net core 1 to 2 all db initialization should be moved out of the StartUp cs and into the Program cs  Otherwise the EF tasks try and run your DB inits when doing tasks    There is a nice section in the official migration docs  https   docs microsoft com en-us ef core miscellaneous 1x-2x-upgrade  titled    Move database initialization code    which I seemed to have missed  So before you head down any rabbit holes like I did make sure this isn   t what is causing your need to add an implementation of IdesignTimeDbContextFactory

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If context class is in another class library project and this error is occurred  change command line default project to the context project and set solution startup project to the main API   ASP net core project  that your DI container is there   then re-run command It seems ef core tools package has this bug a reported in https   github com dotnet efcore issues 23957 and https   github com dotnet efcore issues 23853

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I had same problem  Just changed the ap jason to application jason and it fixed the issue

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I ran into same problem  I have two projects in the solution  which         API   Services and repo  which hold context models      Initially  API project was set as Startup project   I changed the Startup project to the one which holds context classes  if you are using Visual Studio you can set a project as Startup project by      open solution explorer    right-click on context project    select Set as Startup project

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Solution 1   Find the problem in 99  of cases   Set Web Application project  as Startup Project  Run the following commands with -verbose option   Add-Migration Init -Verbose      -verbose option helps to actually uncover the real problem  It   contains detailed errors    Solution 2   Rename BuildWebHost   to CreateWebHostBuilder    because Entity Framework Core tools expect to find a CreateHostBuilder method that configures the host without running the app    NET Core 2 2  public class Program       public static void Main string   args                CreateWebHostBuilder args  Build   Run               public static IWebHostBuilder CreateWebHostBuilder string   args    gt          WebHost CreateDefaultBuilder args               UseStartup lt Startup gt           NET Core 3 1  Rename BuildWebHost   to CreateHostBuilder    public class Program       public static void Main string   args                CreateHostBuilder args  Build   Run               public static IHostBuilder CreateHostBuilder string   args    gt          Host CreateDefaultBuilder args               ConfigureWebHostDefaults webBuilder   gt                                webBuilder UseStartup lt Startup gt                         Solution 3   Make sure you added Dbcontext to dependency injection   AddDbContext lt TContext gt  will make both your DbContext type  TContext  and the corresponding DbContextOptions lt TContext gt  available for injection from the service container  This requires adding a constructor argument to your DbContext type that accepts DbContextOptions lt TContext gt    Example  In Startup cs  public void ConfigureServices IServiceCollection services        services AddDbContext lt AppDbContext gt  options   gt  options UseSqlServer connectionString        AppDbContext code   public class AppDbContext  DbContext       public AppDbContext DbContextOptions lt AppDbContext gt  options         base options

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Using ASP NET Core 3 1 and EntityFrameWorkCore 3 1 0  Overriding the OnConfiguring of the context class with a parameterless constructor only     protected override void OnConfiguring DbContextOptionsBuilder optionsBuilder                if   optionsBuilder IsConfigured                        IConfigurationRoot configuration   new ConfigurationBuilder                   SetBasePath Directory GetCurrentDirectory                    AddJsonFile  appsettings json                   Build                var connectionString   configuration GetConnectionString  LibraryConnection                optionsBuilder UseSqlServer connectionString

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I got the same issue since I was referring old- Microsoft EntityFrameworkCore Tools DotNet   lt DotNetCliToolReference Include  Microsoft EntityFrameworkCore Tools DotNet  Version  1 0 0    gt    After upgrading to the newer version it got resolved

[c#] Unable to create migrations after upgrading to ASP.NET Core 2.0

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