Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/a5e3d298520874d01414ea3fde92d8f7.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563