Type Load Exception in EF Core Project

user_4971859 0
Viewed 31978

I have an ASP.NET Core 3.1 Web API application using EF Core. This is the my configuration in the ConfigureServices method of the Startup class:

services.AddDbContext<ApplicationContext>(options =>
options.UseSqlServer(Configuration.GetConnectionString("AppConn")));

The above configuration tested and works for a SQL Server database.

Then I switched to using Sqlite after installing its package successfully.

services.AddDbContext<ApplicationContext>(options =>
     options.UseSqlite("Data Source=sqlitedemo.db"));

But when I try to add the EF migration

add-migration initial -context ApplicationContext

I get this error:

System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation.

System.TypeLoadException: Could not load type 'Microsoft.EntityFrameworkCore.Internal.SemanticVersionComparer' from assembly 'Microsoft.EntityFrameworkCore, Version=5.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'.

{ Stack trace }

Exception has been thrown by the target of an invocation.

entity-framework-core .net-core c#
7 Answers

Please update to your entity framework core nuget package to 3.1.10(or latest 5.0.0). It will solve your problem.

user_13651590

I had EF Core 5 package installed, but not Microsoft.EntityFrameworkCore.Design and one package were implicitly referencing older version (Microsoft.EntityFrameworkCore.Design 3.0.0).

Installing explicit dependency on Microsoft.EntityFrameworkCore.Design 5.x.x resolved the issue for me.

user_45535180

I had this issue in a .NET Core 3.1 project. I fixed it by installing the package Microsoft.EntityFrameworkCore.Design in the startup project

user_40564870

I had a similar issue when all the dependencies seemed correct in my project. But the issue was that the context was in one project in the solution and a different project in the solution was the start-up project. And that project happened to include a different version of EFCore.

Using the context's project as the start-up project in the Package Manager Console resolved the issue for me.

add-migration -startupproject myProjectWithTheMigration

user_17532550

Make sure that each project referenced pulls in the same major/minor version of the Entity Framework nuget package.

I upgraded a project from V3 to V6 and didn't upgrade the EF Core nuget packages to 6. One project had 6 while the other had 3 and was receiving this error when I did an update-database.

user_2857950

Do not forget that for migrations, you must have the packages installed both in the main EntityFramework project and in the startup project.

Microsoft.EntityFramework.Core
Microsoft.EntityFramework.Core.Design
user_30963350

If you are trying to do migration, make sure install Microsoft.EntityFrameworkCore.Tools

user_97953090
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