tursodatabase/turso · error · ArgumentException

Connection must be a TursoConnection.

Error message

Connection must be a TursoConnection.

What it means

The DbConnection setter on TursoCommand only accepts TursoConnection instances (TursoCommand.cs:62-73) because the command must reach the native database handle owned by that concrete type. Assigning any other DbConnection-derived object (SqlConnection, SQLiteConnection, NpgsqlConnection) throws ArgumentException; assigning null clears the connection without error.

Source

Thrown at bindings/dotnet/src/Turso.Data/TursoCommand.cs:74

        }
    }

    public override bool DesignTimeVisible { get; set; }
    public override UpdateRowSource UpdatedRowSource { get; set; }

    protected override DbConnection? DbConnection
    {
        get => _connection;
        set
        {
            if (value is null)
            {
                _connection = null;
                return;
            }

            _connection = value as TursoConnection
                          ?? throw new ArgumentException("Connection must be a TursoConnection.", nameof(value));
            _commandTimeout = _connection.DefaultTimeout;
        }
    }

    protected override DbParameterCollection DbParameterCollection => _parameterCollection;

    public new virtual TursoParameterCollection Parameters => _parameterCollection;


    protected override DbTransaction? DbTransaction
    {
        get => _transaction;
        set
        {
            if (value is null)
            {
                _transaction = null;
                return;

View on GitHub (pinned to c1e5928725)

Solutions

1. Create commands from the Turso connection itself: using var cmd = tursoConn.CreateCommand();
2. Or construct with the typed overload: new TursoCommand(sql, tursoConn); assigning null first if rebinding is needed.
3. Fix the DI/provider registration so the same provider (TursoFactory) supplies both the connection and the commands.

Example fix

// before
var cmd = new TursoCommand();
cmd.Connection = sqliteConnection; // throws ArgumentException

// after
var cmd = sqliteTursoConn.CreateCommand(); // or: new TursoCommand(sql, tursoConn)

if (cmd.Connection is not null && cmd.Connection is not TursoConnection)
    throw new InvalidOperationException("Command is bound to a foreign provider's connection.");

static bool IsTursoConnection(DbConnection? c) => c is null || c is TursoConnection;

try
{
    cmd.Connection = incomingConnection;
}
catch (ArgumentException ex) when (ex.ParamName == "value")
{
    // incomingConnection is from another provider; re-create the command on the Turso connection.
}

When it happens

Trigger: cmd.Connection = new SqlConnection(...); or new TursoCommand { Connection = foreignConnection } where the connection was created by a different ADO.NET provider.

Common situations: Copy-paste migration from Microsoft.Data.SqlClient where only the class names changed; provider-agnostic DALs that pass DbConnection around; DI container registered with the wrong provider so a foreign connection is injected into code that creates TursoCommands.

Related errors

• Batch command must be a TursoBatchCommand.
• Transaction must be a TursoTransaction.
• Parameter must be of type TursoParameter
• Connection must be set before executing a command.
• Connection must be set before preparing a command.

AI-assisted analysis of tursodatabase/turso@c1e5928725 (2026-08-20). Data as JSON: /api/errors/4ad9f5025b10309e. Report an issue: GitHub.