Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/3b4a9a86d2034e8a71fb319e999ae199.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563