Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/d898f99a3e60e0a33eaa53cae81b7150.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563