Recently , I installed SQL Server Data tools ( SSDT) after installing SQL Server 2014 .
As mentioned in one of my post (http://mfzahirdba.blogspot.com/2016/02/sql-server-2014-surprises.html ) , SSDT is not bundled in the installer . You will need to download and install it.
After the install , I created a SSIS project , and created a data flow task.
When , I am try to create a new connection manager , I was greeted (!) with this error.
Here is how , I resolved the issue .
a) Identify the correct machine.config in the .NET framework
In my case , it was
C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Config\machine.config
b) Remove one of the tags (DbProviderFactories) in section in "system.data"
section.
After the edit ,I was able to create the connection managers with no issue.
It looks like , when you install the ODBC / .NET drivers , it adds the additional tag into the .NET framework configuration file.
Hope this is helpful .