"System Configmachine.config with the App.config/web.config configuration node of its own application" workaround

Your app's app. config or Web. config file
C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Configmachine.config files for the system
1. Repeat the following configuration:

    <dbproviderfactories>      <Addname= "MySQL Data Provider2"invariant= "MySql.Data.MySqlClient"Description= ". Net Framework Data Provider for MySQL"type= "MySql.Data.MySqlClient.MySqlClientFactory, Mysql.data, version=6.5.4.0, Culture=neutral, publickeytoken= C5687fc88969c44d " />    </dbproviderfactories>

Will throw an exception as follows:

Exception is:configurationerrorsexception-Error creating configuration section handler for System.Data: Column "InvariantName" is constrained to be unique. Value "MySql.Data.MySqlClient" already exists

2. If both are not configured, the following exception is thrown:

Exception is:argumentexception-can ' t load dbproviderfactory for given value of ProviderType

In practice, you will encounter the following questions:

Some databases are not configured in the system's Configmachine.config file if problems are installed

      <name= "MySQL Data Provider2"  invariant= "MySql.Data.MySqlClient"  description= ". Net Framework Data Provider for MySQL"  type= " MySql.Data.MySqlClient.MySqlClientFactory, Mysql.data, version=6.5.4.0, Culture=neutral, publickeytoken= c5687fc88969c44d "/>

Due to the above uncertainties, we can configure this node in our own application's App/web.config file to cause exceptions due to duplicate configuration.

Workaround:

Add this node to your application's App/web.config file:

<remove invariant= "MySql.Data.MySqlClient"/> Node

That

  <System.Data>    <dbproviderfactories>       <Remove  invariant= "MySql.Data.MySqlClient"/>       <Addname= "MySQL Data Provider2" invariant= "MySql.Data.MySqlClient" Description= ". Net Framework Data Provider for MySQL"type= "MySql.Data.My sqlclient.mysqlclientfactory, Mysql.data, version=6.5.4.0, Culture=neutral, publickeytoken= C5687fc88969c44d " />    </dbproviderfactories>  </System.Data>