Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/81d95c3da714de8d3d4823eb81aa2407.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563