Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/97481ee1d5bb1f3cb1f7dcb44a252a69.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563