Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/38d65f2c5318a6471af9a563fc11c6a9.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563