Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/38a6fa2a892e70a9133c8197186b7cc3.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563