Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/41c7148709315f62e2433b0dc2ed4a5b.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563