No Entity Framework provider found for the ADO provider with invariant name ' System.Data.SqlClient '

Exception Description:

System.Data.Entity.Core.MetadataException:Schema specified is not valid. Errors:
PAYCENTERMODELS.SSDL (2,2): Error 0152:no Entity Framework provider found for the ADO provider with invariant name ' S Ystem. Data.sqlclient '. Make sure the provider are registered in the ' EntityFramework ' section of the application config file. See http://go.microsoft.com/fwlink/?LinkId=260882 for more information.
In System.Data.Entity.Core.Metadata.Edm.StoreItemCollection.Loader.ThrowOnNonWarningErrors ()
In System.Data.Entity.Core.Metadata.Edm.StoreItemCollection.Loader.LoadItems (IEnumerable ' 1 xmlreaders, IEnumerable ' 1 sourcefilepaths)
In System.Data.Entity.Core.Metadata.Edm.StoreItemCollection.Loader. ctor (IEnumerable ' 1 xmlreaders, IEnumerable ' 1 sourcefilepaths, Boolean throwOnError, Idbdependencyresolver Resolver)
In System.Data.Entity.Core.Metadata.Edm.StoreItemCollection.Init (IEnumerable ' 1 xmlreaders, IEnumerable ' 1 filepaths, Boolean throwOnError, Idbdependencyresolver Resolver, dbprovidermanifest& providermanifest, DbProviderFactory & ProviderFactory, string& providerinvariantname, string& providermanifesttoken, Memoizer ' 2& Cachedctypefunction)
In System.Data.Entity.Core.Metadata.Edm.StoreItemCollection. ctor (IEnumerable ' 1 xmlreaders, IEnumerable ' 1 filepaths)
In System.Data.Entity.Core.Metadata.Edm.MetadataCache.LoadStoreCollection (Edmitemcollection edmitemcollection, Metadataartifactloader loader)
In system.data.entity.core.metadata.edm.metadatacache.<>c__displayclass5.<>c__displayclass7.< Getmetadataworkspace>b__1 ()
In System.lazy ' 1.CreateValue ()
In System.lazy ' 1.LazyInitValue ()
In System.lazy ' 1.get_value ()
In system.data.entity.core.metadata.edm.metadatacache.<>c__displayclass5.<>c__displayclass7.< Getmetadataworkspace>b__4 ()
In System.data.entity.core.metadata.edm.metadataworkspace.loadandcheckitemcollection[t] (Func ' 1 Itemcollectionloader)
In System.data.entity.core.metadata.edm.metadataworkspace.<>c__displayclass16.<.ctor>b__f ()
In System.lazy ' 1.CreateValue ()
In System.lazy ' 1.LazyInitValue ()
In System.lazy ' 1.get_value ()
In System.Data.Entity.Core.Metadata.Edm.MetadataWorkspace.GetItemCollection (DataSpace DataSpace, Boolean required)
In System.Data.Entity.Core.Metadata.Edm.MetadataWorkspace.GetItemCollection (DataSpace dataspace)
At System.Data.Entity.Core.Objects.ObjectContext.InitializeMappingViewCacheFactory (DbContext owner)
In System.Data.Entity.Core.Objects.ObjectContext. ctor (entityconnection connection, Boolean Isconnectionconstructor, objectqueryexecutionplanfactory Objectqueryexecutionplanfactory, Translator Translator, Columnmapfactory columnmapfactory)
In System.Data.Entity.Internal.InternalConnection.CreateObjectContextFromConnectionModel ()
In System.Data.Entity.Internal.LazyInternalConnection.CreateObjectContextFromConnectionModel ()
In System.Data.Entity.Internal.LazyInternalContext.InitializeContext ()
In System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType (Type entityType)
In System.Data.Entity.Internal.Linq.InternalSet ' 1.Initialize ()
In System.Data.Entity.Internal.Linq.InternalSet ' 1.get_internalcontext ()
In System.Data.Entity.Infrastructure.DbQuery ' 1.system.linq.iqueryable.get_provider ()
In System.linq.queryable.where[tsource] (IQueryable ' 1 source, Expression ' 1 predicate)
In PaymentBLL.NewPayApplyBLL.GetPaidOrder (String OrderNo, thirdpayplatformenums thirdpayplatform) Location D:\SourceProject \infrastructure. Paycenter\trunk\paymentplatform\paymentbll\newpayapplybll.cs: Line No. 30
D:\SourceProject\infrastructure in PaymentBLL.QRCodeBLL.Refund (String requestjson) position. Paycenter\trunk\paymentplatform\paymentbll\qrcodebll.cs: Line No. 132
The location of PaymentPlatform.QRCodeDemo.Refund.submit_Click (Object sender, EventArgs e) is d:\SourceProject\infrastructure. Paycenter\trunk\paymentplatform\paymentplatform\qrcodedemo\refund.aspx.cs: Line No. 63

Workaround:

Right-click the solution → manage nuget packages, select "EntityFramework", click "Manage", select the project to install EF in the pop-up box, tap "OK".

After completion, the following node configuration is more in Web. config:

<Configuration>  <configsections>     < Sectionname= "entityframework"type= "System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, version=6.0.0.0, culture= Neutral, publickeytoken=b77a5c561934e089 "requirepermission= "false" />  </configsections>  <EntityFramework>    <defaultconnectionfactorytype= "System.Data.Entity.Infrastructure.LocalDbConnectionFactory, entityframework">      <Parameters>        <parametervalue= "v11.0" />      </Parameters>    </defaultconnectionfactory>    <providers>      <providerInvariantName= "System.Data.SqlClient"type= "System.Data.Entity.SqlServer.SqlProviderServices, entityframework.sqlserver" />    </providers>  </EntityFramework></Configuration>

At the same time, the reference is more than 2 packets of entityframework:

No Entity Framework provider found for the ADO provider with invariant name ' System.Data.SqlClient '