Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/1f0313f564527a0e2f4461561166bf2d.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563