Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/d0f1566d1d9ae69ac0a9ee069b1aaf8a.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563