Error: No corresponding Snowflake type for type AnsiString

Question

I want to copy all the data from the List to the table in the snowflake database.

Entity for Proposal

{
    public string ServiceCode { get; set; }
    public string ServiceDescription { get; set; }
    public string ProviderGrossTariff { get; set; }
    public string ProviderProposal { get; set; }
    public string CleanedProposal { get; set; }
    public string Notes { get; set; }
}

Table in the db:

create or replace TABLE TCT_WEBAPP.DBO.PROPOSALS_KEK (
    SERVICECODE VARCHAR(255),
    SERVICEDESCRIPTION VARCHAR(255),
    PROVIDERGROSSTARIFF VARCHAR(255),
    PROVIDERPROPOSAL VARCHAR(255),
    CLEANEDPROPOSAL VARCHAR(255),
    NOTES VARCHAR(255)
);

I convert my list to the DataTable using this method:

private DataTable ConvertToDataTable(List<Proposal> proposals)
{
    DataTable dataTable = new DataTable();
    dataTable.Columns.Add("ServiceCode");
    dataTable.Columns.Add("ServiceDescription");
    dataTable.Columns.Add("ProviderGrossTariff");
    dataTable.Columns.Add("ProviderProposal");
    dataTable.Columns.Add("CleanedProposal");
    dataTable.Columns.Add("Notes");

    foreach (var proposal in proposals)
    {
        dataTable.Rows.Add(
            proposal.ServiceCode,
            proposal.ServiceDescription,
            proposal.ProviderGrossTariff,
            proposal.ProviderProposal,
            proposal.CleanedProposal,
            proposal.Notes
        );
    }

    return dataTable;
}

And then I'm trying to copy it to the table:

DataTable dataTable = ConvertToDataTable(proposals);

using (IDbCommand command = conn.CreateCommand())
{
    // Set up a SQL command to execute stored procedure for bulk insert
    command.CommandText = "$\"COPY INTO DBO.SOME_TABLE FROM (SELECT * FROM @dataTable)\"";
    command.Parameters.Add(new SnowflakeDbParameter
    {
        ParameterName = "dataTable",
        Value = dataTable
    });
    command.ExecuteNonQuery();
}

But then I get this error: Error: No corresponding Snowflake type for type AnsiString. SqlState: , VendorCode: 270053, QueryId:

Is anybody know what could be causing this error? Or may be you can suggest any other ways to copy data from the list to the db table?