Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/f26714354dc5e35c61c0b53f6c314d6e.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563