Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/19f7c3d8d7ca4c457e4039ae9b20b0ae.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563