Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/60cb81f7b5a16036e2a1c544a7d1f02b.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563