Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/5a3359ec28c63e64b3f8e4a6406afe36.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563