Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/b864fa1534b5bdb7e874e3d201d4f7a2.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563