Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/ea02be7b67f6d77a2ed8c4699cc2c14b.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563