Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/0e4ac5f7118846b264454b9bb07eb7d2.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563