yiisoft/yii2 · error · yii\base\InvalidConfigException

Transaction::db must be set.

Error message

Transaction::db must be set.

What it means

Error "Transaction::db must be set." thrown in yiisoft/yii2.

Source

Thrown at framework/db/Transaction.php:122

     * has no effect. You have to call [[setIsolationLevel()]] in this case after the transaction has started.
     *
     * > Note: Some DBMS allow setting of the isolation level only for the whole connection so subsequent transactions
     * may get the same isolation level even if you did not specify any. When using this feature
     * you may need to set the isolation level for all transactions explicitly to avoid conflicting settings.
     * At the time of this writing affected DBMS are MSSQL and SQLite.
     *
     * [isolation level]: https://en.wikipedia.org/wiki/Isolation_%28database_systems%29#Isolation_levels
     *
     * Starting from version 2.0.16, this method throws exception when beginning nested transaction and underlying DBMS
     * does not support savepoints.
     * @throws InvalidConfigException if [[db]] is `null`
     * @throws NotSupportedException if the DBMS does not support nested transactions
     * @throws Exception if DB connection fails
     */
    public function begin($isolationLevel = null)
    {
        if ($this->db === null) {
            throw new InvalidConfigException('Transaction::db must be set.');
        }
        $this->db->open();

        if ($this->_level === 0) {
            if ($isolationLevel !== null) {
                $this->db->getSchema()->setTransactionIsolationLevel($isolationLevel);
            }
            Yii::debug('Begin transaction' . ($isolationLevel ? ' with isolation level ' . $isolationLevel : ''), __METHOD__);

            $this->db->trigger(Connection::EVENT_BEGIN_TRANSACTION);
            $this->db->pdo->beginTransaction();
            $this->_level = 1;

            return;
        }

        $schema = $this->db->getSchema();
        if ($schema->supportsSavepoint()) {

View on GitHub (pinned to 66f00d18a2)

When it happens

Trigger: Thrown at framework/db/Transaction.php:122 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of yiisoft/yii2@66f00d18a2 (2026-08-17). Data as JSON: /api/errors/25eb45385a5cd0eb. Report an issue: GitHub.