Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/43485cb28b3c77a38c7cf295804f56d3.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563