InvalidCastException from 'OracleConnection' to 'OracleConnection' on DbCommand.set_DbConnection

Question

I have the following code

            using (DbConnection conn = new Oracle.DataAccess.Client.OracleConnection(
                @"<connectionString>"))
            {
                conn.Open();
                DbProviderFactory fact = GetFactory(conn);
                using (DbCommand cmd = fact.CreateCommand())
                {
                    cmd.CommandText = "SELECT * FROM TAB";
                    cmd.Connection = conn;
                    using (DbDataAdapter dda = fact.CreateDataAdapter())
                    {
                        dda.SelectCommand = cmd;
                        using (DataTable dt = new DataTable("TAB"))
                        {
                            dda.Fill(dt);
                        }
                    }
                }
            }

The GetFactory method is this (I had to write this implementation because I'm in .NET 3.5, who it doesn't have DbProviderFactories.GetFactory(DbConnection)):

    static DbProviderFactory GetFactory(DbConnection conn)
    {
        return DbProviderFactories.GetFactory(conn.GetType().Namespace);
    }

On the following line it throws an InvalidCastException from 'Oracle.DataAccess.Client.OracleConnection' to'Oracle.DataAccess.Client.OracleConnection'.

cmd.Connection = conn;

I'm puzzled...

I'm referencing Oracle.DataAccess version 2.121.2.0
Can someone explain me what I'm missing?

Edit 1------------------

I followed the suggestion given by SLaks and I found that when

return DbProviderFactories.GetFactory(conn.GetType().Namespace);

is executed another version of Oracle.DataAccess.dll is loaded (the one on the GAC). The specific version is 2.112.3.0.

Why doesn't it use the version previously loaded?

Edit 2------------------

As SLaks said in his second suggestion I had an issue on my machine.config, it was like:

<add name="Oracle Data Provider for .NET" invariant="Oracle.DataAccess.Client" description="Oracle Data Provider for .NET" type="Oracle.DataAccess.Client.OracleClientFactory, Oracle.DataAccess, Version=2.112.3.0, Culture=neutral, PublicKeyToken=89b483f429c47342" />

So I solved editing it in:

<add name="Oracle Data Provider for .NET" invariant="Oracle.DataAccess.Client" description="Oracle Data Provider for .NET" type="Oracle.DataAccess.Client.OracleClientFactory, Oracle.DataAccess, Version=2.121.2.0, Culture=neutral, PublicKeyToken=89b483f429c47342" />

And installing in the GAC the Oracle.DataAccess.Client 2.121.2.0 (not necessary, but I preferred to do this)

Thanks!

It sounds like you have multiple versions of the assembly loaded. Check Debug, Modules. — SLaks
– SLaks, Commented Mar 12, 2015 at 13:45
I agree with SLaks. Check your references. I have also seen similar issues when missing dependencies. — tdbeckett
– tdbeckett, Commented Mar 12, 2015 at 13:59
Why do you use DbProviderFactory? Does your application have to work with different database types (and database providers)? — Wernfried Domscheit
– Wernfried Domscheit, Commented Mar 12, 2015 at 14:45
@Wernfried Yes, the example i wrote was minimal to facilitate the comprehension — Matteo Umili
– Matteo Umili, Commented Mar 12, 2015 at 14:47

SLaks · Accepted Answer · 2015-03-12 14:12:47Z

1

This would happen if the <DbProviderFactories> element in Machine.config references a different version of the Oracle.DataAccess assembly.

You can change either version to match, or you can add a <bindingRedirect> in App.config.

answered Mar 12, 2015 at 14:12

SLaks

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