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Editorial Team
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Asked: 2026-06-17T08:54:09+00:00

I’ve developed a quick and simple app on my local machine using SQLite to

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I’ve developed a quick and simple app on my local machine using SQLite to get started. Now that I’m in the middle of working out how to upload to AppHarbor, I’m a bit stuck on getting the link to ElephantSQL to work.

I used the Application PostgreSQL Sample Application to determine that I needed to use the PostgreSQLConfiguration class for my FluentNHibernate configuration and install the Npgsql package to my solution (I got version 2.0.12.1).

When I push the code up to AppHarbor, it builds and deploys happily. When the server starts to spin up the AppDomain, it throws the error Could not load file or assembly 'policy.2.0.Npgsql' or one of its dependencies. Modules which are not in the manifest were streamed in. (Exception from HRESULT: 0x80131043). This isn’t logged in the Errors section of the AppHarbor dashboard (perhaps this is a missing feature or a bug?) so I had to turn off CustomErrors to figure out what was going on.

What have I missed?

Additional – I tried downgrading to package version 2.0.11. This did not include the policy.2.0.Npgsql.dll file and when trying to load the app, it fails with the error Unable to find the requested .Net Framework Data Provider. It may not be installed..

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1 Answer

  1. Editorial Team

    I got it working by going down to version 2.0.11 and made sure that the DbProviderFactories configuration section had the correct version number in the type attribute.

    <DbProviderFactories>
  <add name="Npgsql Data Provider" invariant="Npgsql" description=".Net Framework Data Provider for PostgreSQL Server" type="Npgsql.NpgsqlFactory, Npgsql, Version=2.0.11.0, Culture=neutral, PublicKeyToken=5d8b90d52f46fda7" />
</DbProviderFactories>
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