SQLite

The generator is a T4 template that runs externally to your project and cannot use any NuGet packages you have installed in your project. Therefore the SQLite provider has to be registered externally to your project.

machine.config

In both

• c:\Windows\Microsoft.NET\Framework64\v4.0.30319\Config\machine.config
• c:\Windows\Microsoft.NET\Framework\v4.0.30319\Config\machine.config

search for <system.data>, (approximately line 168). I have the following <system.data> XML where you will see an entry for SQLite Data Provider has been added:

<system.data>
    <DbProviderFactories>
      <add name="Microsoft SQL Server Compact Data Provider 4.0" invariant="System.Data.SqlServerCe.4.0" description=".NET Framework Data Provider for Microsoft SQL Server Compact" type="System.Data.SqlServerCe.SqlCeProviderFactory, System.Data.SqlServerCe, Version=4.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91"/>
      <add name="Npgsql Data Provider" invariant="Npgsql" description=".NET Data Provider for PostgreSQL" type="Npgsql.NpgsqlFactory, Npgsql, Version=4.1.8.0, Culture=neutral, PublicKeyToken=5D8B90D52F46FDA7"/>
      <add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient" description=".Net Framework Data Provider for MySQL" type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data, Version=9.0.0.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d"/>
      <add name="ODP.NET, Managed Driver" invariant="Oracle.ManagedDataAccess.Client" description="Oracle Data Provider for .NET, Managed Driver" type="Oracle.ManagedDataAccess.Client.OracleClientFactory, Oracle.ManagedDataAccess, Version=4.122.19.1, Culture=neutral, PublicKeyToken=89b483f429c47342"/>
      <add name="SQLite Data Provider" invariant="System.Data.SQLite" description=".Net Framework Data Provider for SQLite" type="System.Data.SQLite.SQLiteFactory, System.Data.SQLite" />
    </DbProviderFactories>
</system.data>

I modified both. However to find the exact one which is used by the generator, in your <database>.tt file very near the bottom, un-comment

fileManagement.WriteLine("// " + System.Runtime.InteropServices.RuntimeEnvironment.SystemConfigurationFile);

Save the <database>.tt and inspect the first line in the generated output. I have the following listed:

// C:\Windows\Microsoft.NET\Framework64\v4.0.30319\config\machine.config

So that is the exact file the generator will use and is the one that is required to have the above XML added.