Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/202924c7b64c156c6add2596d48d0ef6.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563