ODP.NET

This is an old topic ( ), but I'm still in trouble with it.

string connectionString = (new OracleConnectionStringBuilder()
            {
                UserID = "USER_TMP",
                Password = "********",
                DataSource = "localhost:1521/xe",
                Pooling = true,
                ConnectionTimeout = 15,
                ConnectionLifeTime = 0
            }).ConnectionString;
// Looks like: USER ID=USER_TMP;POOLING=True;CONNECTION TIMEOUT=15;PASSWORD=********;DATA SOURCE=localhost:1521/xe;CONNECTION LIFETIME=0
using (TransactionScope scope = new TransactionScope())
{
    using (OracleConnection cnx = new OracleConnection(connectionString))
    {
        cnx.Open(); // here occurs exception
    }
}

Database : Oracle Database 10g Express Edition Release 10.2.0.1.0 - Product (something I can't change)

Nuget: Oracle.ManagedDataAccess (tried from 12.2.1100 to 19.7.0)

Framework: .Net 4.5.1

The only particular thing is that this code run on a different thread.

I don't really understand the exception message since I'm on a local database.

I also tried with these options to transaction:

using (TransactionScope scope = new TransactionScope(TransactionScopeAsyncFlowOption.Enabled))

using (TransactionScope scope = new TransactionScope(TransactionScopeOption.RequiresNew))