Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/a5d0dced0b5e41b48b59093e7d19ce69.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563