Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/8d29c3482eb885a49caa2cca32fd7a61.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563