framework/widgets/ActiveForm.php
public function errorSummary($models, $options = [])
    {
        Html::addCssClass($options, $this->errorSummaryCssClass);
        $options['encode'] = $this->encodeErrorSummary;
        return Html::errorSummary($models, $options);
    }
public function errorSummary($models, $options = [])
    {
        Html::addCssClass($options, $this->errorSummaryCssClass);
        $options['encode'] = $this->encodeErrorSummary;
        return Html::errorSummary($models, $options);
    }
Generates a summary of the validation errors.
If there is no validation error, an empty error summary markup will still be generated, but it will be hidden.
@param Model|Model[] $models the model(s) associated with this form.
@param array $options the tag options in terms of name-value pairs. The following options are specially handled:

- `header`: string, the header HTML for the error summary. If not set, a default prompt string will be used.
- `footer`: string, the footer HTML for the error summary.

The rest of the options will be rendered as the attributes of the container tag. The values will
be HTML-encoded using [[\yii\helpers\Html::encode()]]. If a value is `null`, the corresponding attribute will not be rendered.
@return string the generated error summary.
@see errorSummaryCssClass