Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/cf5e3b3fa3bffb58771c8b0dc7dc4bee.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563