An Exception of type System.Nullreferenceexception occurred in Entityframework.dll when trying to insert given

Question

I am trying to save a data in a table on the server using entityFramework, but is making an error of Nullreferenceexception. The insertion code is:

public void CadastraFaleConosco(FaleConosco fale)
        {
            using (var context = new PoliToldosContext())
            {

                    context.FaleConosco.Add(fale);
                    context.SaveChanges();
               }
}

when I debuggar is shows the following:

I do not know what to do to make the location and sql without the error, I think that’s it. I was able to create an Migration of the table and it worked, I don’t know what the error might be, the contextDB class is:

 [DbConfigurationType(typeof(MySql.Data.Entity.MySqlEFConfiguration))]
    public class PoliToldosContext : DbContext
    {
        public DbSet<FaleConosco> FaleConosco { get; set; }

        public PoliToldosContext() : base("Poli")
        { }

    }

As requested the error stack is:

Description: An untreated exception occurred during the execution of current web request. Examine stack tracking to get more information about the error and where it originated in the code.

Exception Details: System.Nullreferenceexception: Object reference not defined for an instance of an object.

Error of Origin:

Linha 23:                 try
Linha 24:                 {
Linha 25:                     context.FaleConosco.Add(fale);
Linha 26:                     context.SaveChanges();
Linha 27:                 }

Arquivo de Origem: C:\Users\Tacila\Documents\projects\PoliToldos\PoliToldos\Service\SistemaService.cs    Linha: 25 

Rastreamento de Pilha: 


[NullReferenceException: Referência de objeto não definida para uma instância de um objeto.]
   MySql.Data.MySqlClient.MySqlProviderServices.GetDbProviderManifestToken(DbConnection connection) +56
   System.Data.Entity.Core.Common.DbProviderServices.GetProviderManifestToken(DbConnection connection) +276
   System.Data.Entity.Utilities.DbProviderServicesExtensions.GetProviderManifestTokenChecked(DbProviderServices providerServices, DbConnection connection) +27
   System.Data.Entity.Infrastructure.<>c__DisplayClass1.<ResolveManifestToken>b__0(Tuple`3 k) +32
   System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory) +72
   System.Data.Entity.Infrastructure.DefaultManifestTokenResolver.ResolveManifestToken(DbConnection connection) +251
   System.Data.Entity.Utilities.DbConnectionExtensions.GetProviderInfo(DbConnection connection, DbProviderManifest& providerManifest) +56
   System.Data.Entity.DbModelBuilder.Build(DbConnection providerConnection) +43
   System.Data.Entity.Internal.LazyInternalContext.CreateModel(LazyInternalContext internalContext) +159
   System.Data.Entity.Internal.RetryLazy`2.GetValue(TInput input) +123
   System.Data.Entity.Internal.LazyInternalContext.InitializeContext() +627
   System.Data.Entity.Internal.InternalContext.Initialize() +20
   System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType(Type entityType) +16
   System.Data.Entity.Internal.Linq.InternalSet`1.Initialize() +53
   System.Data.Entity.Internal.Linq.InternalSet`1.get_InternalContext() +15
   System.Data.Entity.Internal.Linq.InternalSet`1.ActOnSet(Action action, EntityState newState, Object entity, String methodName) +62
   System.Data.Entity.Internal.Linq.InternalSet`1.Add(Object entity) +108
   System.Data.Entity.DbSet`1.Add(TEntity entity) +72
   PoliToldos.Service.SistemaService.CadastraFaleConosco(FaleConosco fale) in C:\Users\Tacila\Documents\projects\PoliToldos\PoliToldos\Service\SistemaService.cs:25
   PoliToldos.Controllers.SistemaController.CadastraFaleConosco(FaleConosco fale) in C:\Users\Tacila\Documents\projects\PoliToldos\PoliToldos\Controllers\SistemaController.cs:30
   lambda_method(Closure , ControllerBase , Object[] ) +103
   System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) +14
   System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) +157
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +27
   System.Web.Mvc.Async.AsyncControllerActionInvoker.<BeginInvokeSynchronousActionMethod>b__39(IAsyncResult asyncResult, ActionInvocation innerInvokeState) +22
   System.Web.Mvc.Async.WrappedAsyncResult`2.CallEndDelegate(IAsyncResult asyncResult) +29
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) +32
   System.Web.Mvc.Async.AsyncInvocationWithFilters.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3d() +50
   System.Web.Mvc.Async.<>c__DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f() +228
   System.Web.Mvc.Async.<>c__DisplayClass33.<BeginInvokeActionMethodWithFilters>b__32(IAsyncResult asyncResult) +10
   System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +10
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult) +34
   System.Web.Mvc.Async.<>c__DisplayClass2b.<BeginInvokeAction>b__1c() +26
   System.Web.Mvc.Async.<>c__DisplayClass21.<BeginInvokeAction>b__1e(IAsyncResult asyncResult) +100
   System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +10
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +27
   System.Web.Mvc.Controller.<BeginExecuteCore>b__1d(IAsyncResult asyncResult, ExecuteCoreState innerState) +13
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +29
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +36
   System.Web.Mvc.Controller.<BeginExecute>b__15(IAsyncResult asyncResult, Controller controller) +12
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +22
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +26
   System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +10
   System.Web.Mvc.MvcHandler.<BeginProcessRequest>b__5(IAsyncResult asyncResult, ProcessRequestState innerState) +21
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +29
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +28
   System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +9874041
   System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step) +48
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +159

Please somebody help me!

Answer 1

I solved it! The web.config configuration was wrong, it was actually missing:

<system.data>
    <DbProviderFactories>
      <remove invariant="MySql.Data.MySqlClient" />
      <add name="MySQL" description="ADO.Net driver for MySQL" invariant="MySql.Data.MySqlClient" type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data"/>
    </DbProviderFactories>
  </system.data>

Adding the Provider Factories worked, another thing I changed was also removing the version before had something like Version=6.10.8.0, pulled out letting the tool find the best version for the project. I hope you help others!