Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/a22b139a3da0dc222b1a9bb65991467e.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563