How to REALLY solve DbProviderFactories section can only appear once per config file error

Had this issue after installing SQL 2017, then installing SQL 2012 side-by-side and trying to create an SSIS package to load data from flat files to SQL. No idea if the dual installation caused it but it definitely caused many hours of frustration!

Many places on the web will have you only going to ONE folder to fix the machine.config file, took me much digging to find out there are two folders to check!

C:\Windows\Microsoft.NET\Framework\v4.0.30319\Config
C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Config

So here's how to do it:
First, go to one of the two folders listed above and you'll see the different versions. First go to the folder v4.0.30319 and open the CONFIG folder > Machine.Config file in a text editor (NOT WORD, use Notepad or something similar....oh hell, just use Notepad to be safe). In that file, search for the string “<DbProviderFactories/>”. If you found that, you'll see something similar to this (please note that this can be an issue with ANY provider, I'm showing DB2 here):




<system.data>
    <DbProviderFactories>
        <add name="IBM DB2 for i5/OS .NET Provider" invariant="IBM.Data.DB2.iSeries" description=".NET Framework Data Provider for i5/OS" type="IBM.Data.DB2.iSeries.iDB2Factory, IBM.Data.DB2.iSeries, Version=12.0.0.0, Culture=neutral, PublicKeyToken=9cdb2ebfb1f93a26"/>
        <add name="Microsoft SQL Server Compact Data Provider" invariant="System.Data.SqlServerCe.3.5" description=".NET Framework Data Provider for Microsoft SQL Server Compact" type="System.Data.SqlServerCe.SqlCeProviderFactory, System.Data.SqlServerCe, Version=3.5.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91"/>
    </DbProviderFactories>
    <DbProviderFactories/>
</system.data>


The <DbProviderFactories/> doesn’t belong there so delete this line:

<DbProviderFactories/>

Save it and look in the other folders of the other versions for that line. It’s possible that this line also appears in v2.0.50727. Don't forget to check both folders (Framework and Framework64)!