tursodatabase/turso · error · ArgumentException

Parameter {value} is not a TursoParameter

Error message

Parameter {value} is not a TursoParameter

What it means

TursoParameterCollection.SetParameter(int index, DbParameter value) backs the integer indexer setter and throws this ArgumentException when the value is not a TursoParameter ('value as TursoParameter' yields null). The collection is strongly typed by design; it never wraps or converts foreign DbParameter types.

Source

Thrown at bindings/dotnet/src/Turso.Data/TursoParameterCollection.cs:114

        _parameters.RemoveAt(index);
    }

    protected override DbParameter GetParameter(int index)
    {
        return _parameters[index];
    }

    protected override DbParameter GetParameter(string parameterName)
    {
        return _parameters.Find(p => p.ParameterName == parameterName)
               ?? throw new ArgumentException($"Parameter {parameterName} not found");
    }

    protected override void SetParameter(int index, DbParameter value)
    {
        _parameters[index] = value as TursoParameter
                             ?? throw new ArgumentException($"Parameter {value} is not a TursoParameter");
    }

    protected override void SetParameter(string parameterName, DbParameter value)
    {
        var index = IndexOf(parameterName);
        if (index == -1)
            throw new ArgumentException($"Parameter {parameterName} not found");
        _parameters[index] = value as TursoParameter
                             ?? throw new ArgumentException($"Parameter {value} is not a TursoParameter");
    }
}

View on GitHub (pinned to 244cde92a7)

Solutions

1. Create the replacement with new TursoParameter(...) before assigning it to the indexer.
2. In provider-agnostic code, build parameters via cmd.CreateParameter() so the type always matches the collection.
3. Copy Name/Value/DbType from the foreign parameter into a fresh TursoParameter instead of assigning it directly.

Example fix

// before
cmd.Parameters[0] = new SqlParameter("@id", 42);

// after
cmd.Parameters[0] = new TursoParameter("@id", 42);

static bool IsTursoParam(DbParameter p) => p is TursoParameter;

When it happens

Trigger: Assigning cmd.Parameters[0] = new SqlParameter(...) / new SqliteParameter(...) / any custom DbParameter subclass; passing a DbParameter-typed variable that actually holds another provider's type; generic factory code parameterized on DbProviderFactory reusing parameter objects across providers.

Common situations: Multi-provider code that creates parameters with one factory and assigns them to another provider's command; refactoring from SqlClient where collections sometimes accepted conversions; helper libraries storing parameters as DbParameter.

Related errors

• Parameter {value} not found
• Parameter {parameterName} not found
• Parameter must be of type TursoParameter
• Only input parameters are supported
• Connection must be a SqliteConnection.

AI-assisted analysis of tursodatabase/turso@244cde92a7 (2026-08-20). Data as JSON: /api/errors/062c55a744c883ec. Report an issue: GitHub.