Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/0a12a9ace847d3f1549f5cb3f55b23f1.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563