Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/fe1f09e4123aa54d5b02b9c370e4497c.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563