Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/dc8b0e6b11bb912e6689d88d905bca35.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563