Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/2d3314db07d98fba59a413a7f3bf9b19.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563