我有一个包含数据库逻辑的类库。我已经使用了迁移，但由于它仍处于开发状态，我删除了“迁移”＃39;文件夹并删除了我数据库中的所有表。
在包管理器控制台中选择数据库项目，然后键入启用 - 迁移
注意：还尝试删除数据库并创建一个新的，仍然是这个问题。
Checking if the context targets an existing database...
System.TypeInitializationException: The type initializer for 'System.Data.SqlClient.SqlConnection' threw an exception. ---> System.TypeInitializationException: The type initializer for 'System.Data.SqlClient.SqlConnectionFactory' threw an exception. ---> System.TypeInitializationException: The type initializer for 'System.Data.SqlClient.SqlPerformanceCounters' threw an exception. ---> System.Configuration.ConfigurationErrorsException: Unrecognized element 'add'. (D:\Visual Studio\MessageService-Net\MessageService-Net\tmp1F93.tmp line 182)
at System.Configuration.BaseConfigurationRecord.EvaluateOne(String[] keys, SectionInput input, Boolean isTrusted, FactoryRecord factoryRecord, SectionRecord sectionRecord, Object parentResult)
at System.Configuration.BaseConfigurationRecord.Evaluate(FactoryRecord factoryRecord, SectionRecord sectionRecord, Object parentResult, Boolean getLkg, Boolean getRuntimeObject, Object& result, Object& resultRuntimeObject)
at System.Configuration.BaseConfigurationRecord.GetSectionRecursive(String configKey, Boolean getLkg, Boolean checkPermission, Boolean getRuntimeObject, Boolean requestIsHere, Object& result, Object& resultRuntimeObject)
at System.Configuration.BaseConfigurationRecord.GetSectionRecursive(String configKey, Boolean getLkg, Boolean checkPermission, Boolean getRuntimeObject, Boolean requestIsHere, Object& result, Object& resultRuntimeObject)
at System.Configuration.BaseConfigurationRecord.GetSectionRecursive(String configKey, Boolean getLkg, Boolean checkPermission, Boolean getRuntimeObject, Boolean requestIsHere, Object& result, Object& resultRuntimeObject)
at System.Configuration.BaseConfigurationRecord.GetSection(String configKey)
at System.Configuration.ClientConfigurationSystem.System.Configuration.Internal.IInternalConfigSystem.GetSection(String sectionName)
at System.Configuration.ConfigurationManager.GetSection(String sectionName)
at System.Configuration.PrivilegedConfigurationManager.GetSection(String sectionName)
at System.Diagnostics.DiagnosticsConfiguration.Initialize()
at System.Diagnostics.DiagnosticsConfiguration.get_SwitchSettings()
at System.Diagnostics.Switch.InitializeConfigSettings()
at System.Diagnostics.Switch.InitializeWithStatus()
at System.Diagnostics.Switch.get_SwitchSetting()
at System.Data.ProviderBase.DbConnectionPoolCounters..ctor(String categoryName, String categoryHelp)
at System.Data.SqlClient.SqlPerformanceCounters..ctor()
at System.Data.SqlClient.SqlPerformanceCounters..cctor()
--- End of inner exception stack trace ---
at System.Data.SqlClient.SqlConnectionFactory..cctor()
--- End of inner exception stack trace ---
at System.Data.SqlClient.SqlConnection..cctor()
--- End of inner exception stack trace ---
at System.Data.SqlClient.SqlConnection..ctor()
at System.Data.SqlClient.SqlClientFactory.CreateConnection()
at System.Data.Entity.Internal.LazyInternalConnection.CreateConnectionFromProviderName(String providerInvariantName)
at System.Data.Entity.Internal.LazyInternalConnection.InitializeFromConnectionStringSetting(ConnectionStringSettings appConfigConnection)
at System.Data.Entity.Internal.LazyInternalConnection.TryInitializeFromAppConfig(String name, AppConfig config)
at System.Data.Entity.Internal.LazyInternalConnection.Initialize()
at System.Data.Entity.Internal.LazyInternalConnection.get_Connection()
at System.Data.Entity.Internal.LazyInternalContext.get_Connection()
at System.Data.Entity.Infrastructure.DbContextInfo..ctor(Type contextType, DbProviderInfo modelProviderInfo, AppConfig config, DbConnectionInfo connectionInfo, Func`1 resolver)
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.Run()
at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
at System.Data.Entity.Migrations.Design.ToolingFacade.Run(BaseRunner runner)
at System.Data.Entity.Migrations.Design.ToolingFacade.ScaffoldInitialCreate(String language, String rootNamespace)
at System.Data.Entity.Migrations.EnableMigrationsCommand.<>c__DisplayClass2.<.ctor>b__0()
at System.Data.Entity.Migrations.MigrationsDomainCommand.Execute(Action command)
The type initializer for 'System.Data.SqlClient.SqlConnection' threw an exception.
的app.config
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<configSections>
<section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
</configSections>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.6.1" />
</startup>
<entityFramework>
<defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework" />
<providers>
<provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
</providers>
</entityFramework>
</configuration>