Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/c0b0ae78741fb6c1584cfd0c1c1e2454.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563