ASP.NET Web API执行Add-Migration InitialCreate时遇序列化及空引用错误

问题场景 #

在ASP.NET Web API项目中执行Add-Migration InitialCreate命令添加Entity Framework迁移时，出现序列化相关错误，数据库连接正常。

错误信息 #

PM> Add-Migration InitialCreate
Exception calling "SetData" with "2" argument(s): "Type 'Microsoft.VisualStudio.ProjectSystem.VS.Implementation.Package.Automation.OAProject' in assembly 'Microsoft.VisualStudio.ProjectSystem.VS.Implementation, Version=17.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' is not marked as serializable."
At C:\Users\Ctop\.nuget\packages\entityframework\6.0.0\tools\EntityFramework.psm1:609 char:5
+     $domain.SetData('project', $project)
+     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : SerializationException

Exception calling "SetData" with "2" argument(s): "Type 'Microsoft.VisualStudio.ProjectSystem.VS.Implementation.Package.Automation.OAProject' in assembly 'Microsoft.VisualStudio.ProjectSystem.VS.Implementation, Version=17.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' is not marked as serializable."
At C:\Users\Ctop\.nuget\packages\entityframework\6.0.0\tools\EntityFramework.psm1:610 char:5
+     $domain.SetData('contextProject', $contextProject)
+     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : SerializationException

Exception calling "SetData" with "2" argument(s): "Type 'Microsoft.VisualStudio.ProjectSystem.VS.Implementation.Package.Automation.OAProject' in assembly 'Microsoft.VisualStudio.ProjectSystem.VS.Implementation, Version=17.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' is not marked as serializable."
At C:\Users\Ctop\.nuget\packages\entityframework\6.0.0\tools\EntityFramework.psm1:611 char:5
+     $domain.SetData('startUpProject', $startUpProject)
+     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : SerializationException

System.NullReferenceException: Object reference not set to an instance of an object.
   at System.Data.Entity.Migrations.Extensions.ProjectExtensions.GetPropertyValue[T](Project project, String propertyName)
   at System.Data.Entity.Migrations.MigrationsDomainCommand.GetFacade(String configurationTypeName, Boolean useContextWorkingDirectory)
   at System.Data.Entity.Migrations.AddMigrationCommand.Execute(String name, Boolean force, Boolean ignoreChanges)
   at System.Data.Entity.Migrations.MigrationsDomainCommand.Execute(Action command)
Object reference not set to an instance of an object.
PM> 

解决方法 #

• 升级EntityFramework包：当前使用的EF6.0.0和VS2022（版本17.x）存在兼容性问题，将NuGet包EntityFramework升级到6.4.4及以上稳定版本，该版本修复了VS2022下的序列化问题。
• 确认Package Manager Console设置：在控制台顶部的“默认项目”下拉菜单中选中包含DbContext的项目，同时确保启动项目设置正确。
• 改用命令行工具执行迁移：
  1. 打开命令提示符，切换到项目根目录
  2. 执行Install-Package EntityFramework确保包安装完成
  3. 执行Enable-Migrations -ContextTypeName 你的DbContext类名（若未启用迁移）
  4. 执行Add-Migration InitialCreate
• 清理重建项目：清理解决方案（生成->清理解决方案），然后重建所有项目，修复可能存在的引用损坏问题。
• 重置VS设置：若上述方法无效，尝试重置VS设置（工具->导入和导出设置->重置所有设置），排除IDE配置问题。

内容的提问来源于stack exchange，提问作者Ali Moussawi