framework/captcha/CaptchaAction.php
public function init()
    {
        $this->fontFile = Yii::getAlias($this->fontFile);
        if (!is_file($this->fontFile)) {
            throw new InvalidConfigException("The font file does not exist: {$this->fontFile}");
        }
    }
public function init()
    {
        $this->fontFile = Yii::getAlias($this->fontFile);
        if (!is_file($this->fontFile)) {
            throw new InvalidConfigException("The font file does not exist: {$this->fontFile}");
        }
    }
Initializes the action.
@throws InvalidConfigException if the font file does not exist.