用Scaffold命令生成数据库实体类，新建个asp.net core 2.2 webapi项目，在.net core 2.2下是好的，能生成实体类。再新建asp.net core 3.0 webapi项目，关联的驱动和组件都升级到3.0 预览版，同样的Scaffold命令就报错了，不知道问题再哪里？目前就现在2.2里生成实体类，在复制到3.0的项目中用。

PM> Scaffold-DbContext -Force "Data Source=xx;Database=cloud;User Id=xx;Password=xx;CharSet=utf8;port=xx" MySql.Data.EntityFrameworkCore -OutputDir Models -Context MySqlContext
System.TypeLoadException: Method 'Create' in type 'MySql.Data.EntityFrameworkCore.Scaffolding.Internal.MySQLDatabaseModelFactory' from assembly 'MySql.Data.EntityFrameworkCore, Version=8.0.17.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d' does not have an implementation.
at MySql.Data.EntityFrameworkCore.Design.Internal.MySQLDesignTimeServices.ConfigureDesignTimeServices(IServiceCollection serviceCollection)
at Microsoft.EntityFrameworkCore.Design.Internal.DesignTimeServicesBuilder.ConfigureDesignTimeServices(Type designTimeServicesType, IServiceCollection services)
at Microsoft.EntityFrameworkCore.Design.Internal.DesignTimeServicesBuilder.ConfigureProviderServices(String provider, IServiceCollection services, Boolean throwOnError)
at Microsoft.EntityFrameworkCore.Design.Internal.DesignTimeServicesBuilder.Build(String provider)
at Microsoft.EntityFrameworkCore.Design.Internal.DatabaseOperations.ScaffoldContext(String provider, String connectionString, String outputDir, String outputContextDir, String dbContextClassName, IEnumerable1 schemas, IEnumerable1 tables, Boolean useDataAnnotations, Boolean overwriteFiles, Boolean useDatabaseNames)
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.ScaffoldContextImpl(String provider, String connectionString, String outputDir, String outputDbContextDir, String dbContextClassName, IEnumerable1 schemaFilters, IEnumerable1 tableFilters, Boolean useDataAnnotations, Boolean overwriteFiles, Boolean useDatabaseNames)
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.ScaffoldContext.<>c__DisplayClass0_0.<.ctor>b__0()
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.<>c__DisplayClass3_0`1.<Execute>b__0()
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
Method 'Create' in type 'MySql.Data.EntityFrameworkCore.Scaffolding.Internal.MySQLDatabaseModelFactory' from assembly 'MySql.Data.EntityFrameworkCore, Version=8.0.17.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d' does not have an implementation.

PM> Scaffold-DbContext -Force "Data Source=(DESCRIPTION =(ADDRESS = (PROTOCOL = TCP)(HOST = xx)(PORT=xx))(CONNECT_DATA =(SERVER = DEDICATED)(SERVICE_NAME =xx)));User Id=xx;Password=xx;" Oracle.EntityFrameworkCore -OutputDir DataModels -Context MyDbContext -Schemas xx
System.TypeLoadException: Method 'Create' in type 'Oracle.EntityFrameworkCore.Scaffolding.Internal.OracleDatabaseModelFactory' from assembly 'Oracle.EntityFrameworkCore, Version=2.0.19.1, Culture=neutral, PublicKeyToken=89b483f429c47342' does not have an implementation.
at Oracle.EntityFrameworkCore.Design.Internal.OracleDesignTimeServices.ConfigureDesignTimeServices(IServiceCollection serviceCollection)
at Microsoft.EntityFrameworkCore.Design.Internal.DesignTimeServicesBuilder.ConfigureDesignTimeServices(Type designTimeServicesType, IServiceCollection services)
at Microsoft.EntityFrameworkCore.Design.Internal.DesignTimeServicesBuilder.ConfigureProviderServices(String provider, IServiceCollection services, Boolean throwOnError)
at Microsoft.EntityFrameworkCore.Design.Internal.DesignTimeServicesBuilder.Build(String provider)
at Microsoft.EntityFrameworkCore.Design.Internal.DatabaseOperations.ScaffoldContext(String provider, String connectionString, String outputDir, String outputContextDir, String dbContextClassName, IEnumerable1 schemas, IEnumerable1 tables, Boolean useDataAnnotations, Boolean overwriteFiles, Boolean useDatabaseNames)
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.ScaffoldContextImpl(String provider, String connectionString, String outputDir, String outputDbContextDir, String dbContextClassName, IEnumerable1 schemaFilters, IEnumerable1 tableFilters, Boolean useDataAnnotations, Boolean overwriteFiles, Boolean useDatabaseNames)
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.ScaffoldContext.<>c__DisplayClass0_0.<.ctor>b__0()
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.<>c__DisplayClass3_0`1.<Execute>b__0()
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
Method 'Create' in type 'Oracle.EntityFrameworkCore.Scaffolding.Internal.OracleDatabaseModelFactory' from assembly 'Oracle.EntityFrameworkCore, Version=2.0.19.1, Culture=neutral, PublicKeyToken=89b483f429c47342' does not have an implementation.

Steps to reproduce
Include a complete code listing (or project/solution) that we can run to reproduce the issue.

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--mysql (replace sensitive information to xx)
Scaffold-DbContext -Force "Data Source=xx;Database=cloud;User Id=xx;Password=xx;CharSet=utf8;port=xx" MySql.Data.EntityFrameworkCore -OutputDir Models -Context MySqlContext
--oracle (replace sensitive information to xx)
Scaffold-DbContext -Force "Data Source=(DESCRIPTION =(ADDRESS = (PROTOCOL = TCP)(HOST = xx)(PORT=xx))(CONNECT_DATA =(SERVER = DEDICATED)(SERVICE_NAME =xx)));User Id=xx;Password=xx;" Oracle.EntityFrameworkCore -OutputDir DataModels -Context MyDbContext -Schemas xx
Further technical details
$ dotnet --info
.NET Core SDK (global.json):
Version: 3.0.100-preview8-013656
Commit: 8bf06ffc8d

OS Name: Windows
OS Version: 10.0.17134
OS Platform: Windows
RID: win10-x64
Base Path: C:\Program Files\dotnet\sdk\3.0.100-preview8-013656
Host (useful for support):
Version: 3.0.0-preview8-28405-07
Commit: d01b2fb7bc

.NET Core SDKs installed:
2.1.801 [C:\Program Files\dotnet\sdk]
2.2.300 [C:\Program Files\dotnet\sdk]
2.2.401 [C:\Program Files\dotnet\sdk]
3.0.100-preview8-013656 [C:\Program Files\dotnet\sdk]

IDE: (Visual Studio Community 2019 16.2.3)

<PackageReference Include="Autofac" Version="4.9.4" />
<PackageReference Include="Autofac.Extensions.DependencyInjection" Version="5.0.0-rc1" />
<PackageReference Include="AutoMapper" Version="9.0.0" />
<PackageReference Include="AutoMapper.Extensions.Microsoft.DependencyInjection" Version="7.0.0" />
<PackageReference Include="Dapper" Version="2.0.4" />
<PackageReference Include="log4net" Version="2.0.8" />
<PackageReference Include="Microsoft.EntityFrameworkCore" Version="3.0.0-preview8.19405.11" />
<PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="3.0.0-preview8.19405.11" />
<PackageReference Include="Microsoft.EntityFrameworkCore.Relational" Version="3.0.0-preview8.19405.11" />
<PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="3.0.0-preview8.19405.11"/>
<PackageReference Include="Microsoft.Extensions.Caching.Abstractions" Version="3.0.0-preview8.19405.4" />
<PackageReference Include="Microsoft.Extensions.Options" Version="3.0.0-preview8.19405.4" />
<PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="3.0.0-preview8-19413-06" />
<PackageReference Include="MySql.Data" Version="8.0.17" />
<PackageReference Include="MySql.Data.EntityFrameworkCore" Version="8.0.17" />
<PackageReference Include="MySql.Data.EntityFrameworkCore.Design" Version="8.0.17" />
<PackageReference Include="Newtonsoft.Json" Version="12.0.3-beta1" />
<PackageReference Include="Oracle.EntityFrameworkCore" Version="2.19.30" />
<PackageReference Include="Oracle.ManagedDataAccess.Core" Version="2.19.31" />
<PackageReference Include="Swashbuckle.AspNetCore" Version="5.0.0-rc2" />
<PackageReference Include="Swashbuckle.AspNetCore.Filters" Version="5.0.0-rc8" />

https://github.com/aspnet/EntityFrameworkCore/issues/17556