Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/edbf5a48aa692a44cc9d73e1a1d06513.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563