Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/9374b80c9f7657cf1b9e1629c24a3575.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563