Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/89b4687a0c29eb4b50e900f32acc163d.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563