解决方法如下:

方法一、找到以下路径文件:C:\Windows\Microsoft.NET\Framework\v4.0.30319\Config\machine.config

将下面这段配置文件加入<configSections>节点下。


<configSections>
<section name="oracle.unmanageddataaccess.client" type="OracleInternal.Common.CustomSectionHandler, Oracle.DataAccess, Version=4.122.18.3, Culture=neutral, PublicKeyToken=89b483f429c47342" />
<section name="oracle.dataaccess.client" type="System.Data.Common.DbProviderConfigurationHandler, System.Data, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
<section name="oracle.manageddataaccess.client" type="OracleInternal.Common.ODPMSectionHandler, Oracle.ManagedDataAccess, Version=4.122.18.3, Culture=neutral, PublicKeyToken=89b483f429c47342" /></configSections>



 将以下配置加入<system.data>节点下


<system.data>
<DbProviderFactories>
<add name="ODP.NET, Unmanaged Driver" invariant="Oracle.DataAccess.Client" description="Oracle Data Provider for .NET, Unmanaged Driver" type="Oracle.DataAccess.Client.OracleClientFactory, Oracle.DataAccess, Version=4.122.18.3, Culture=neutral, PublicKeyToken=89b483f429c47342" />
<add name="ODP.NET, Managed Driver" invariant="Oracle.ManagedDataAccess.Client" description="Oracle Data Provider for .NET, Managed Driver" type="Oracle.ManagedDataAccess.Client.OracleClientFactory, Oracle.ManagedDataAccess, Version=4.122.18.3, Culture=neutral, PublicKeyToken=89b483f429c47342" />
</DbProviderFactories>
</system.data>


方法二、在vs2019 使用的config 中加入


<configSections>
<section name="oracle.unmanageddataaccess.client" type="OracleInternal.Common.CustomSectionHandler, Oracle.DataAccess, Version=4.122.18.3, Culture=neutral, PublicKeyToken=89b483f429c47342" />
<section name="oracle.dataaccess.client" type="System.Data.Common.DbProviderConfigurationHandler, System.Data, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
<section name="oracle.manageddataaccess.client" type="OracleInternal.Common.ODPMSectionHandler, Oracle.ManagedDataAccess, Version=4.122.18.3, Culture=neutral, PublicKeyToken=89b483f429c47342" />
</configSections>



<system.data>
<DbProviderFactories>
<add name="ODP.NET, Unmanaged Driver" invariant="Oracle.DataAccess.Client" description="Oracle Data Provider for .NET, Unmanaged Driver" type="Oracle.DataAccess.Client.OracleClientFactory, Oracle.DataAccess, Version=4.122.18.3, Culture=neutral, PublicKeyToken=89b483f429c47342" />
<add name="ODP.NET, Managed Driver" invariant="Oracle.ManagedDataAccess.Client" description="Oracle Data Provider for .NET, Managed Driver" type="Oracle.ManagedDataAccess.Client.OracleClientFactory, Oracle.ManagedDataAccess, Version=4.122.18.3, Culture=neutral, PublicKeyToken=89b483f429c47342" />
</DbProviderFactories>
</system.data>


注意 方法一和方法二 内容只能保留一个