Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/0f133dddd9f9c3e0929b45313c1c2a99.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563