framework/data/DataFilter.php
protected function defaultErrorMessages()
    {
        return [
            'invalidFilter' => Yii::t('yii', 'The format of {filter} is invalid.'),
            'operatorRequireMultipleOperands' => Yii::t('yii', 'Operator "{operator}" requires multiple operands.'),
            'unknownAttribute' => Yii::t('yii', 'Unknown filter attribute "{attribute}"'),
            'invalidAttributeValueFormat' => Yii::t('yii', 'Condition for "{attribute}" should be either a value or valid operator specification.'),
            'operatorRequireAttribute' => Yii::t('yii', 'Operator "{operator}" must be used with a search attribute.'),
            'unsupportedOperatorType' => Yii::t('yii', '"{attribute}" does not support operator "{operator}".'),
        ];
    }
protected function defaultErrorMessages()
    {
        return [
            'invalidFilter' => Yii::t('yii', 'The format of {filter} is invalid.'),
            'operatorRequireMultipleOperands' => Yii::t('yii', 'Operator "{operator}" requires multiple operands.'),
            'unknownAttribute' => Yii::t('yii', 'Unknown filter attribute "{attribute}"'),
            'invalidAttributeValueFormat' => Yii::t('yii', 'Condition for "{attribute}" should be either a value or valid operator specification.'),
            'operatorRequireAttribute' => Yii::t('yii', 'Operator "{operator}" must be used with a search attribute.'),
            'unsupportedOperatorType' => Yii::t('yii', '"{attribute}" does not support operator "{operator}".'),
        ];
    }
Returns default values for [[errorMessages]].
@return array default error messages in `[errorKey => message]` format.