Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/6e22eac333a2f57af00177c0f86b0890.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563