System.TypeLoadException: 无法加载类型 'Microsoft.EntityFrameworkCore.Infrastructure.DesignTimeProviderServicesAttribute'

Question

我已经使用 .net core 3.1 从现有数据库更新模型。

尝试在包管理器控制台中使用以下注释添加实体，

dotnet ef dbcontext scaffold "Server=xxxxxxxx;Database=Test;Trusted_Connection=True;" Microsoft.EntityFrameworkCore.SqlServer --output-dir UserEntity --table users

得到以下异常，

Build started...
Build succeeded.
System.TypeLoadException: Could not load type 'Microsoft.EntityFrameworkCore.Infrastructure.DesignTimeProviderServicesAttribute' from assembly 'Microsoft.EntityFrameworkCore, Version=3.1.6.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'.
   at System.ModuleHandle.ResolveTypeHandleInternal(RuntimeModule module, Int32 typeToken, RuntimeTypeHandle[] typeInstantiationContext, RuntimeTypeHandle[] methodInstantiationContext)
   at System.Reflection.RuntimeModule.ResolveType(Int32 metadataToken, Type[] genericTypeArguments, Type[] genericMethodArguments)
   at System.Reflection.CustomAttribute.FilterCustomAttributeRecord(MetadataToken caCtorToken, MetadataImport& scope, RuntimeModule decoratedModule, MetadataToken decoratedToken, RuntimeType attributeFilterType, Boolean mustBeInheritable, ListBuilder`1& derivedAttributes, RuntimeType& attributeType, IRuntimeMethodInfo& ctor, Boolean& ctorHasParameters, Boolean& isVarArg)
   at System.Reflection.CustomAttribute.AddCustomAttributes(ListBuilder`1& attributes, RuntimeModule decoratedModule, Int32 decoratedMetadataToken, RuntimeType attributeFilterType, Boolean mustBeInheritable, ListBuilder`1 derivedAttributes)
   at System.Reflection.CustomAttribute.GetCustomAttributes(RuntimeModule decoratedModule, Int32 decoratedMetadataToken, Int32 pcaCount, RuntimeType attributeFilterType)
   at System.Reflection.CustomAttribute.GetCustomAttributes(RuntimeAssembly assembly, RuntimeType caType)
   at System.Reflection.RuntimeAssembly.GetCustomAttributes(Type attributeType, Boolean inherit)
   at System.Attribute.GetCustomAttributes(Assembly element, Type attributeType, Boolean inherit)
   at System.Attribute.GetCustomAttribute(Assembly element, Type attributeType, Boolean inherit)
   at System.Reflection.CustomAttributeExtensions.GetCustomAttribute[T](Assembly element)
   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, IEnumerable`1 schemas, IEnumerable`1 tables, Boolean useDataAnnotations, Boolean overwriteFiles, Boolean useDatabaseNames)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.ScaffoldContextImpl(String provider, String connectionString, String outputDir, String outputDbContextDir, String dbContextClassName, IEnumerable`1 schemaFilters, IEnumerable`1 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)
Could not load type 'Microsoft.EntityFrameworkCore.Infrastructure.DesignTimeProviderServicesAttribute' from assembly 'Microsoft.EntityFrameworkCore, Version=3.1.6.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'.

注：

使用以下实体版本，

1. Microsoft.EntityFrameworkCore.Design - 3.1.6
2. Microsoft.EntityFrameworkCore.SqlServer - 1.1.6

Could any one help me to resolve this issue?

提前致谢。

Answer 1

为什么您使用旧版本的 Microsoft.EntityFrameworkCore.SqlServer？尝试将其更新为 Microsoft.EntityFrameworkCore.SqlServer 3.1.6.

当我搜索错误时，它看起来像 DesignTimeProviderServicesAttribute 只支持到 Entity Framework Core 1.1，它在 Microsoft.EntityFrameworkCore.Infrastructure.

下

因为您使用的是较新版本 Microsoft.EntityFrameworkCore.Infrastructure 不包括 DesignTimeProviderServicesAttribute。在此处的 MSDN 上验证相同

• DesignTimeProviderServicesAttribute efcore-1.1
• DesignTimeProviderServicesAttribute efcore-3.1.