Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/eedc3b4754d8e0af137e9ca0f77e6e40.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563