Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/65f9edbd93b3a0d7e91aaab41d86c7af.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563