Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/c1ea0f4be6e2b695c7519528e5ee0739.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563