Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/1d9d8c4393328e71c8f5ae497e3f7a57.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563