Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/8e4c7b74ee99e7d1d15a494a8f8c0038.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563