Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/33ce4b4f94da1847b3da96e8ade4f789.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563