Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/19aecdff8d8de14ee981f12d3846fd6b.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563