ef6下mysql数据库迁移发生错误：DbMigrationsConfiguration threw an exception

Question

错误提示：

The type initializer for 'System.Data.Entity.Migrations.DbMigrationsConfiguration`1' threw an exception.

异常详细信息：

PM> add-migration InitialModel
System.TypeInitializationException: The type initializer for 'System.Data.Entity.Migrations.DbMigrationsConfiguration`1' threw an exception. ---> System.InvalidOperationException: The DbConfiguration type 'MySql.Data.Entity.MySqlEFConfiguration, MySql.Data.Entity.EF6' specified in the application config file could not be loaded. Make sure that the assembly-qualified name is used and that the assembly is available to the running application. See http://go.microsoft.com/fwlink/?LinkId=260883 for more information. ---> System.TypeLoadException: Inheritance security rules violated by type: 'MySql.Data.Entity.MySqlEFConfiguration'. Derived types must either match the security accessibility of the base type or be less accessible.
   at System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMarkHandle stackMark, IntPtr pPrivHostBinder, Boolean loadTypeFromPartialName, ObjectHandleOnStack type)
   at System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean loadTypeFromPartialName)
   at System.RuntimeType.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark)
   at System.Type.GetType(String typeName, Boolean throwOnError)
   at System.Data.Entity.Infrastructure.DependencyResolution.DbConfigurationLoader.TryLoadFromConfig(AppConfig config)
   --- End of inner exception stack trace ---
   at System.Data.Entity.Infrastructure.DependencyResolution.DbConfigurationLoader.TryLoadFromConfig(AppConfig config)
   at System.Data.Entity.Infrastructure.DependencyResolution.DbConfigurationManager.EnsureLoadedForAssembly(Assembly assemblyHint, Type contextTypeHint)
   at System.Data.Entity.Infrastructure.DependencyResolution.DbConfigurationManager.EnsureLoadedForContext(Type contextType)
   at System.Data.Entity.Migrations.DbMigrationsConfiguration`1..cctor()
   --- End of inner exception stack trace ---
   at System.Data.Entity.Migrations.DbMigrationsConfiguration`1..ctor()
   at EF.Demo.MySql.Migrations.Configuration..ctor() in D:\SourceCode\ZhaoCode\ToolsAndFrameworks\EntityFramework\EF.Demo.MySql\Migrations\Configuration.cs:line 10
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Data.Entity.Migrations.Utilities.MigrationsConfigurationFinder.FindMigrationsConfiguration(Type contextType, String configurationTypeName, Func`2 noType, Func`3 multipleTypes, Func`3 noTypeWithName, Func`3 multipleTypesWithName)
   at System.Data.Entity.Migrations.Design.ToolingFacade.BaseRunner.FindConfiguration()
   at System.Data.Entity.Migrations.Design.ToolingFacade.ScaffoldRunner.RunCore()
   at System.Data.Entity.Migrations.Design.ToolingFacade.BaseRunner.Run()

上下文代码：

    [DbConfigurationType(typeof(MySqlEFConfiguration))]
    public class Context : DbContext
    {
        public Context() : base("name=MyContext")
        {

        }
        public DbSet<User> Users { get; set; }
    }

配置文件：

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <configSections>
    <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
    <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>-->
  <entityFramework codeConfigurationType="MySql.Data.Entity.MySqlEFConfiguration, MySql.Data.Entity.EF6">
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
      <parameters>
        <parameter value="mssqllocaldb" />
      </parameters>
    </defaultConnectionFactory>
    <providers>
      <!--<provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />-->
      <provider invariantName="MySql.Data.MySqlClient" type="MySql.Data.MySqlClient.MySqlProviderServices, MySql.Data.Entity.EF6, Version=6.10.6.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d">
      </provider>
    </providers>
  </entityFramework>
  <system.data>
    <DbProviderFactories>
      <remove invariant="MySql.Data.MySqlClient" />
      <add description=".Net Framework Data Provider for MySQL" invariant="MySql.Data.MySqlClient" name="MySQL Data Provider" type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data, Version=6.10.6.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" />
    </DbProviderFactories>
  </system.data>


  <connectionStrings>
    <add name="MyContext" connectionString="Data Source=127.0.0.1;port=33060;Initial Catalog=CodeFirstDemoDb;user id=root_test;password=123456;" providerName="MySql.Data.MySqlClient"/>
  </connectionStrings>


</configuration>

寻求一个解决办法，多谢。

Answer 1

你的代码可能存在各种各样的问题：

1. 错误的连接字符串或双连接字符串，检查是否有多个连接字符串，只需要保留一个就行；
2. 列表项目启用迁移的项目可能与启动项目不同。