What causes "Connection must be a SqliteConnection." in tursodatabase/turso?

Create the connection with the Turso.Data.Sqlite namespace: new SqliteConnection(connectionString) and import that namespace, not Microsoft.Data.Sqlite

tursodatabase/turso · error · ArgumentException

Connection must be a SqliteConnection.

Error message

Connection must be a SqliteConnection.

What it means

SqliteBatch.Connection is typed as DbConnection but this facade only works with a Turso SqliteConnection. The setter downcasts the assigned value and throws ArgumentException immediately if the value is a non-null object of any other DbConnection-derived type (e.g. Microsoft.Data.Sqlite.SqliteConnection or a custom provider connection).

Source

Thrown at bindings/dotnet/src/Turso.Data.Sqlite/SqliteBatch.cs:41

        ArgumentNullException.ThrowIfNull(connection);
        _connection = connection;
        _transaction = connection.Transaction;
        _timeout = connection.DefaultTimeout;
    }

    public new SqliteBatchCommandCollection BatchCommands => _batchCommands;

    protected override DbBatchCommandCollection DbBatchCommands => _batchCommands;

    protected override DbConnection? DbConnection
    {
        get => _connection;
        set
        {
            _connection = value as SqliteConnection
                          ?? (value is null
                              ? null
                              : throw new ArgumentException(
                                  "Connection must be a SqliteConnection.",
                                  nameof(value)));
            if (_connection is not null)
                _timeout = _connection.DefaultTimeout;
        }
    }

    protected override DbTransaction? DbTransaction
    {
        get => _transaction;
        set => _transaction = value as SqliteTransaction
                             ?? (value is null
                                 ? null
                                 : throw new ArgumentException(
                                     "Transaction must be a SqliteTransaction.",
                                     nameof(value)));
    }

View on GitHub (pinned to 6c72522679)

Solutions

Create the connection with the Turso.Data.Sqlite namespace: new SqliteConnection(connectionString) and import that namespace, not Microsoft.Data.Sqlite
Check using directives and package references: remove Microsoft.Data.Sqlite or fully qualify the Turso type
If the value comes from DI, register/implement the factory so it returns Turso.Data.Sqlite.SqliteConnection

Example fix

// before
using Microsoft.Data.Sqlite;
batch.Connection = new SqliteConnection(connString); // ArgumentException
// after
using Turso.Data.Sqlite;
batch.Connection = new SqliteConnection(connString);

Defensive patterns

Strategy: type-guard

Validate before calling

if (value is not Turso.Data.Sqlite.SqliteConnection)
    throw new ArgumentException($"Expected Turso SqliteConnection, got {value?.GetType().FullName}");

Type guard

static bool IsTursoSqliteConnection(DbConnection? c) => c is Turso.Data.Sqlite.SqliteConnection;

Try / catch

try { batch.Connection = conn; }
catch (ArgumentException ex) when (ex.ParamName == "value") { /* log wrong provider type, fix DI registration */ }

Prevention

Fully qualify or alias the Turso connection type when both Microsoft.Data.Sqlite and Turso are referenced
Register the exact Turso.Data.Sqlite.SqliteConnection type in DI, not DbConnection
Check batch.Connection assignment types at compile time by keeping variables strongly typed

When it happens

Trigger: Assigning any DbConnection instance that is not bindings/dotnet Turso.Data.Sqlite.SqliteConnection to SqliteBatch.Connection, e.g. batch.Connection = new Microsoft.Data.Sqlite.SqliteConnection(connStr) or a connection from a DI container registered with the wrong type.

Common situations: Mixing Microsoft.Data.Sqlite and Turso.Data.Sqlite packages in one project; resolving a connection from a generic DI/factory that returns the base DbConnection type; copy-pasted code from a Microsoft.Data.Sqlite sample.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

AI-assisted analysis of tursodatabase/turso@6c72522679 (2026-09-06). Data as JSON: /api/errors/49ea57aa3aa0e2ab. Report an issue: GitHub.