Exception when accessing a MySQL database with Entity Framework

Question

I am trying to my .NET Framework web application to work with entity framework and a MySQL database

I followed the steps for enabling Entity Framework with MySql in this article: https://dev.mysql.com/doc/connector-net/en/connector-net-entityframework60.html

It all looked rainbow unicorn and sunshine until I tried to:

Do an Add-Migration after a enable-migrations in the Package Manager Console.
Start the webapplication.

I use the following components:

.NET Framework 4.5.2
Entity Framework 6.2.0
MySql.Data.Entity 6.10.8
MySQL database 5.7

I get the following errors:

Add-Migration error:

System.NullReferenceException: Object reference not set to an instance of an object.
   at MySql.Data.MySqlClient.MySqlProviderServices.GetDbProviderManifestToken(DbConnection connection)
   at System.Data.Entity.Core.Common.DbProviderServices.GetProviderManifestToken(DbConnection connection)
   at MySql.Data.Entity.MySqlManifestTokenResolver.ResolveManifestToken(DbConnection connection)
   at System.Data.Entity.Utilities.DbConnectionExtensions.GetProviderInfo(DbConnection connection, DbProviderManifest& providerManifest)
   at System.Data.Entity.DbModelBuilder.Build(DbConnection providerConnection)
   at System.Data.Entity.Internal.LazyInternalContext.CreateModel(LazyInternalContext internalContext)
   at System.Data.Entity.Internal.RetryLazy`2.GetValue(TInput input)
   at System.Data.Entity.Internal.LazyInternalContext.InitializeContext()
   at System.Data.Entity.Internal.LazyInternalContext.get_ModelBeingInitialized()
   at System.Data.Entity.Infrastructure.EdmxWriter.WriteEdmx(DbContext context, XmlWriter writer)
   at System.Data.Entity.Utilities.DbContextExtensions.<>c__DisplayClass1.<GetModel>b__0(XmlWriter w)
   at System.Data.Entity.Utilities.DbContextExtensions.GetModel(Action`1 writeXml)
   at System.Data.Entity.Utilities.DbContextExtensions.GetModel(DbContext context)
   at System.Data.Entity.Migrations.DbMigrator..ctor(DbMigrationsConfiguration configuration, DbContext usersContext, DatabaseExistenceState existenceState, Boolean calledByCreateDatabase)
   at System.Data.Entity.Migrations.DbMigrator..ctor(DbMigrationsConfiguration configuration)
   at System.Data.Entity.Migrations.Design.MigrationScaffolder..ctor(DbMigrationsConfiguration migrationsConfiguration)
   at System.Data.Entity.Migrations.Design.ToolingFacade.ScaffoldRunner.RunCore()
   at System.Data.Entity.Migrations.Design.ToolingFacade.BaseRunner.Run()
Object reference not set to an instance of an object.

Web application data access error:

Object reference not set to an instance of an object.
   at MySql.Data.MySqlClient.MySqlProviderServices.GetDbProviderManifestToken(DbConnection connection)
   at System.Data.Entity.Core.Common.DbProviderServices.GetProviderManifestToken(DbConnection connection)
   at MySql.Data.Entity.MySqlManifestTokenResolver.ResolveManifestToken(DbConnection connection)
   at System.Data.Entity.Utilities.DbConnectionExtensions.GetProviderInfo(DbConnection connection, DbProviderManifest& providerManifest)
   at System.Data.Entity.DbModelBuilder.Build(DbConnection providerConnection)
   at System.Data.Entity.Internal.LazyInternalContext.CreateModel(LazyInternalContext internalContext)
   at System.Data.Entity.Internal.RetryLazy`2.GetValue(TInput input)
   at System.Data.Entity.Internal.LazyInternalContext.InitializeContext()
   at System.Data.Entity.Internal.InternalContext.Initialize()
   at System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType(Type entityType)
   at System.Data.Entity.Internal.Linq.InternalSet`1.Initialize()
   at System.Data.Entity.Internal.Linq.InternalSet`1.Include(String path)
   at System.Data.Entity.Infrastructure.DbQuery`1.Include(String path)
   at System.Data.Entity.QueryableExtensions.Include[T](IQueryable`1 source, String path)
   at System.Data.Entity.QueryableExtensions.Include[T,TProperty](IQueryable`1 source, Expression`1 path)
   at Jotihunt.Data.DataAccess.MapData.GetCars() in C:\SourceControl\BitBucket\Jotihunt\Data.DataAccess\MapData.cs:line 117
   at Jotihunt.Business.Logic.CarFacade.GetAll() in C:\SourceControl\BitBucket\Jotihunt\Business.Logic\CarFacade.cs:line 30
   at Jotihunt.Presentation.Web.Api.CarController.Get() in C:\SourceControl\BitBucket\Jotihunt\Jotihunt.Presentation.Web\Api\CarController.cs:line 21
   at lambda_method(Closure , Object , Object[] )
   at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.<>c__DisplayClass13.<GetExecutor>b__c(Object instance, Object[] methodParameters)
   at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.Execute(Object instance, Object[] arguments)
   at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.<>c__DisplayClass5.<ExecuteAsync>b__4()
   at System.Threading.Tasks.TaskHelpers.RunSynchronously[TResult](Func`1 func, CancellationToken cancellationToken)

I tried what is suggested in this question: Add-Migration not working with MySQL Unfortunatly that didn't work..

What version of the `MySql.Data` NuGet package are you using? — Bradley Grainger, Oct 12 '18 at 16:43
Thank you for your question. I created a new solution with only ONE project. In that project I am using MySql.Data.EntityFramework in stead of MySql.Data.Entity. This question has the DbContext in a different project than where the connectionstring is held. Because of this I don't get detailed exceptions. By only having one project, the exception showed me the exact problem. — Cees, Oct 15 '18 at 12:22
Also https://dev.mysql.com/doc/connector-net/en/connector-net-entityframework60.html is not up to date. It should cover the MySql.Data.EntityFramework instead of MySql.Data.Entity. — Cees, Oct 15 '18 at 12:23
I covered the new package in my answer here: https://stackoverflow.com/a/50222387. Since Oracle maintains that documentation site, you could report a documentation bug at https://bugs.mysql.com/. — Bradley Grainger, Oct 15 '18 at 14:02
Possible duplicate of [Error-Attempt by method 'X.set\_DbConnection(System.Data.Common.DbConnection)' to access method 'Y.get\_Settings()' failed](https://stackoverflow.com/questions/50216643/error-attempt-by-method-x-set-dbconnectionsystem-data-common-dbconnection-to) — Bradley Grainger, Oct 15 '18 at 15:01

score 1 · Answer 1 · answered Mar 04 '20 at 08:44

1

Make sure the following software have the same version:

MySQL Connector/NET
MySql.Data/MySql.Data.Entity/MySql.Data.EntityFrameworks

maybe this could be helpful when someone google this thread as I was.

answered Mar 04 '20 at 08:44

Keep Thinking

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Exception when accessing a MySQL database with Entity Framework

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