1、2两步为推荐做法
1. 将MySql.Data.dll放到 bin目录下面，或都安装 mysql-connector-net-6.0.0.msi
2.web.config 添加如下节点，注册版本号一致
<system.data>
???<DbProviderFactories>
<remove invariant="MySql.Data.MySqlClient"/>
?????<add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient" description=".Net Framework Data Provider for MySQL" type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data, Version=6.0.0.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d"/>
???</DbProviderFactories>
?</system.data>
3.全局配置
在C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\CONFIG中machine.config(xml文件)中有一个字段是<DbProviderFactories> 有写入MySQL Data Provider 项，
如果是 .NET 4.0需要手动改一下 machine.config文件。将 v2.0.50727 下面的那段复制过去就OK了。
添加注册，<name= "SqlClient Data Provider">或者<name="MySQL Data Provider">
<system.data>
<DbProviderFactories>
<add name="Odbc Data Provider" invariant="System.Data.Odbc" description=".Net Framework Data Provider for Odbc" type="System.Data.Odbc.OdbcFactory, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
<add name="OleDb Data Provider" invariant="System.Data.OleDb" description=".Net Framework Data Provider for OleDb" type="System.Data.OleDb.OleDbFactory, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
<add name="OracleClient Data Provider" invariant="System.Data.OracleClient" description=".Net Framework Data Provider for Oracle" type="System.Data.OracleClient.OracleClientFactory, System.Data.OracleClient, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
<add name="SqlClient Data Provider" invariant="System.Data.SqlClient" description=".Net Framework Data Provider for SqlServer" type="System.Data.SqlClient.SqlClientFactory, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
<add name="SQL Server CE Data Provider" invariant="Microsoft.SqlServerCe.Client" description=".NET Framework Data Provider for Microsoft SQL Server 2005 Mobile Edition" type="Microsoft.SqlServerCe.Client.SqlCeClientFactory, Microsoft.SqlServerCe.Client, Version=9.0.242.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91" />
<add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient" description=".Net Framework Data Provider for MySQL" type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data, Version=6.0.0.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d"/>
<add name="SqlClient Data Provider" invariant="System.Data.SqlClient" description=".Net Framework Data Provider for SqlServer" type="System.Data.SqlClient.SqlClientFactory, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/>
</DbProviderFactories>
</system.data>
找不到请求的 .Net Framework Data Provider。可能没有安装
原文地址：http://www.cnblogs.com/wlming/p/7655397.html