Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/d024ad8edb1e7bc2c9aa5c35262e39bb.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563