Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/bb43b4a3963282b8d529f2c20c379958.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563