Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/1795e79cd46c73455cb6d2e4e99f4f25.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563