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I'm following one of Mosh Hamedani Course on ASP.NET MVC in Udemy.
I came across one error while designing my Database using code-first (Entity Framework).
At first, I got the error of " No DbContext was found in assembly". After resolving this problem another one surged from nowhere.
The image below will show you the error found while adding a migration. I've already searched for the same error but in vain. I'm struggling for the past two hours but nothing is solved till now.
Please, someone, help me. Thanks
unable to create an object of type 'Vidly_Context'. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728
Similar problem after adding own DbContext constructor with (2) parameters. App was ok, but migrations stopped working. Fixed by 1st updating EF (3.1.5 used for strange reason when working with 5) using info from Dotnet tool @xspdf and replacing mentioned constructor by method + hardcoded default connection string if not set.
dotnet tool update --global dotnet-ef // following command show the most during migration build/run in cmd // mind current dir is Migrations folder of (VS) startup project here dotnet ef --startup-project ../ --verbose migrations add test 3.1.5 & context activation Error
The Entity Framework tools version '3.1.5' is older than that of the runtime '5.0.0'. Update the tools for the latest features and bug fixes. Finding DbContext classes... Finding IDesignTimeDbContextFactory implementations... Finding application service provider in assembly '...'... Finding Microsoft.Extensions.Hosting service provider... No static method 'CreateHostBuilder(string[])' was found on class 'Program'. No application service provider was found. Finding DbContext classes in the project... Found DbContext '...Context'. Microsoft.EntityFrameworkCore.Design.OperationException: Unable to create an object of type '...Context'. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728 ---> System.InvalidOperationException: Unable to resolve service for type 'System.String' while attempting to activate '...'. (my additional parameter) at Microsoft.Extensions.DependencyInjection.ActivatorUtilities.ConstructorMatcher.CreateInstance(IServiceProvider provider) at Microsoft.Extensions.DependencyInjection.ActivatorUtilities.CreateInstance(IServiceProvider provider, Type instanceType, Object[] parameters) at Microsoft.Extensions.DependencyInjection.ActivatorUtilities.GetServiceOrCreateInstance(IServiceProvider provider, Type type) at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.<>c__DisplayClass13_4.<FindContextTypes>b__13() --- End of inner exception stack trace --- at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.<>c__DisplayClass13_4.<FindContextTypes>b__13() at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.CreateContext(Func`1 factory) at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.CreateContext(String contextType) at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.AddMigration(String name, String outputDir, String contextType, String namespace) at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigrationImpl(String name, String outputDir, String contextType, String namespace) at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigration.<>c__DisplayClass0_0.<.ctor>b__0() at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.<>c__DisplayClass3_0`1.<Execute>b__0() at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action) Unable to create an object of type '...Context'. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728 
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Delete your Migrations folder. Create a new migration and generate a SQL script for it. In your database, delete all rows from the migrations history table. Insert a single row into the migrations history, to record that the first migration has already been applied, since your tables are already there.
Open the Package Manager Console from Tools → Library Package Manager → Package Manager Console and then run the enable-migrations command (make sure that the default project is the project where your context class is).
IDesignTimeDbContextFactory<TContext> InterfaceImplement this interface to enable design-time services for context types that do not have a public default constructor. At design-time, derived DbContext instances can be created in order to enable specific design-time experiences such as Migrations.
1- Make sure to set your web project as Set as Startup Project
2- In Package Manager Console, set your data access layer (if any) as a default project
3- Then run the command again
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