Unable to find the requested .Net Framework Data Provider. It may not be installed. (System.Data) Exception has been thrown by the target of an invocation. (SQLEditors)

In sql server management studio (SSMS) when we create table in design mode or doing some other operations we may get error message like:

Exception has been thrown by the target of an invocation. (SQLEditors)
------------------------------ADDITIONAL INFORMATION:
Unable to find the requested .Net Framework Data Provider.  It may not be installed. (System.Data)

Solution: 

You have to modify your machine.config  little. Its default location is:

C:\Windows\Microsoft.net\Framework\vXXXX\machine.config

Step 1: You may get data someting like this:

<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=4.121.1.0, Culture=neutral, PublicKeyToken=89b483f429c47342"/>

  <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>

or 

 <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=2.121.1.0, Culture=neutral, PublicKeyToken=89b483f429c47342"/>

  <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"/>

</DbProviderFactories>

<DbProviderFactories>

  <add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient" description=".Net Framework Data Provider for MySQL" type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data, Version=6.6.5.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d"/>

</DbProviderFactories>

Step 2: Remove the text which in blue. That if there are two  <DbProviderFactories> tags then combine all of them in single tag. For example:

<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=2.121.1.0, Culture=neutral, PublicKeyToken=89b483f429c47342"/>

  <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="MySQL Data Provider" invariant="MySql.Data.MySqlClient" description=".Net Framework Data Provider for MySQL" type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data, Version=6.6.5.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d"/>

</DbProviderFactories>

Step 3: Restart sql server. Close your sql server management studio and reopen it.

I hope this fill fix your issue.