Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/a3a572e89e4d1c14640e57d3efa4664c.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563